#help-19
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herrooo im looking for how to find the volume of a meniscus (the curve in the upper surface of a liquid close to the surface of the container or another object, produced by surface tension(wikipedia)) and preferrably a method for how to derive a general equation for any graduated cylinder radius
@keen pike Has your question been resolved?
Can I ask why? (I don't know of such a formula and deriving one seems to me as a non applied mathematician like a pretty complicated physics problem)
mathematical exploration as a part of school
The markings on the graduated cylinder account for the meniscus so a priori it seems easiest to me to take that measurement, find out the true volume of the graduated cylinder up to the top of the meniscus, and take the difference
"A general equation for any graduated cylinder radius" is kinda nonsense though, can't help there
i want to mathematically determine the volume of the meniscus
Do you have a reason to believe that there's an easy way to do this?
not really no itll probably be stupid difficult but i dont even know where to start
ive gotten the advice that the horizontal cross section is kinda like a subtended arc (if thats the name i forgot)
and then i can take the rotational integral about the y axis
and subtract from cylinder height
but i wanna accurately graph the meniscus itself
Is this actually true?
Why should it be a circle?
Yeah, it certainly won't always be like this
Exaclty that’s why I came here
I mean this isn't really a math question
idk what to say to that brodie
I am unconvinced there's some magical formula which parametrizes the surface of a meniscus or something, but if you find out a way to actually describe it then helping you find the volume is something we can do
yeah but there has to be some sort of magic formula bruh thats what im banking on
just some sort of way to graph the meniscus
Why do you think so?
i know that for example chains under slight tension can be graphed by hyperbolic cosine function
like hanging chains p much no tension
that is true
If physics stack exchange is to be believed, the situation is not so great https://physics.stackexchange.com/a/156632
looks pretty grim
ngl just opened the link nd it looks like theyre incorporating density n stuff
if you have the density n stuff predetermined by lets say using jsut water can you make it easier
yes exactly
so if the density is a constant
cant u eliminate multiple like differential equations that come up regarding density
It's already a constant, so having it be specifically water's doesn't really do anything
o yeah thats right sorry i got my variables mixed up
in the article they r finding like the forces exerted on the liquid and other things but not directly the shape of the meniscus
They're finding a diffeq for the height at radius r
only at the start because then it goes fully into the forces exerted on the liquid etc
or nah i was lying my bad
deepest gratitude to you mr hornet
very informative stack exchange articles out there
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Hello. Is this correct? (I marked the steps I followed)
hi! what's the original question?
A number that when divided by 7 has a remainder of 2 and when divided by 5, a remainder of 4.
also, for step 2 and 3, k might not be the same for 7 and 5
so i think it should be x=7a+2 and x=5b+4 (or whatever variables you would like)
they could be equal
but not necessarily
btw, if k is the same for both, it would be uniquely determined by setting the two equations equal to each other, therefore uniquely determining x
tf? Clear working-out in the MathCord server!?
Unthinkable
Given the context, I presume you might have run across the Chinese Remainder Theorem?
https://www.math.cmu.edu/~mradclif/teaching/127S19/Notes/ChineseRemainderTheorem.pdf
[Context - first Google search result]
Wait, that said, you don't have an undergrad role
Well, with the mods being as small and few as they are, try listing out the sequences 7n+2 and 5n+4
If there's a number in common, it'll be within the first 5 numbers of the first sequence (and the first 7 of the second sequence)
(and then adding/subtracting multiples of 35 will give you more solutions)
If there isn't, then this is unsolvable
Ooh, thanks, that's helped
Thanks, I'm just starting to study number theory and I found a video on modular arithmetic where that exercise appeared.
I will investigate more about this.
thanks to both
Bye
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I’m practicing index laws rn since they’re a weakpoint for me and I’ve lost a load of marks on em, I’m doing this question rn and Ik I probably have to factorise it I just don’t really know how to factor the y^-5
My guess was to just rewrite it as 1/y^5 and then just factorise that but Idk how that’d work either
Do u k what happens to the powers of same variable when they r multiplied
You mean smth like
Is this any close to what I have to do?
So here u got x and y variables and they r in multiplied form ,so u could add their powers
Wait fuck I forgot the ^7 on the first y
U dont need to factor out
I can just do 5x • 3x and y • y^-5 and mush it together?
Yes
It's in multiplied form after all
What u were doing would hv been effective in case of addition or subtraction i supposed
alr yeah that makes sense
Okay thank you very much I can sort it out now
Great
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The 2nd question.
Here,A={1,2,3,4,5,6,7}
How can it be true for all values of x?
$8-x \leq 7 \implies -x \leq -1 \implies x \geq 1$, which is satisfied by all $x \in A$
Civil Service Pigeon
Also, in the future, please refer to the question by the marking the paper (so iii here) instead
B/c it took a minute to realise that you were counting the cut off but at the top as a question
Oh,my bad
I misread it as 2
But when I take x=7,the condition does not get satisfied
What
8-7=1
1 is less than 7
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I need help with part b of this question, thanks
have you done a?
have you learned like the general form of the answers to a trigonometric equation
ultimately doing part A then part B would be easier but in case you're supposed to be using general form
@civic jetty Has your question been resolved?
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if we have a density matrix $\rho$, we can consider its projection on a subspace using a projection operator $P$. the projection of $\rho$ is given by $P \rho P$.
we can also consider the partial trace of $\rho$ to obtain the reduced density matrix for a subsystem, $\rho_A = \Tr_\text{(not A)} \rho$.
is there any simplification that can be made to $\Tr_\text{(not A)} (P \rho P)$?
back to ginger
@deep mason Has your question been resolved?
shouldnt there be something in the superscript for one of the Ps?
my prof wrote it with a ^-1 but that doesn't seem like it's right
projection matrices aren't invertible
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if it was a ^\dag, i think P^\dag = P
@deep mason Has your question been resolved?
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Translation is basically telling you to find the m
I literally don't know wtf should i do with ts
Like is it even possible🥀
,help
A brief description and guide on how to use me was sent to your DMs!
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,rccw
Help pls
you can probably take a guess that 5/3 = 20/m or something
Take a guess🥀
This ain't art
Prove why the small trapezoid is similar to the medium trapezoid
If you can't then the question is prolly impossible from lack of info
im just showing you that the sol is probably not impossible
qouldnt m be 20
or am i slow
dont the 2 arrow things on the lines mean they r the same length
Yeah it prolly there's literally no way (from my perspective) to prove that smol trap is similar to med trap
parallel
yeah
Parallel bruh
oh
Except if u can prove that the trapezoid is a square or the 🔶 or rectangle
Yeah pluh i don't think this question is possible🥀
you can
How
you can find this side in terms of variables right
you should probably start by naming some points
Yo ass is not slick bruh undelete that one message💔
we know EG/EB = 3/5, can you find the ratio for DH/DC?
No
sob
it would help to draw EH and GC probably
,rccw
9th
now show EGH similar to GBC
crazy
💔
anyways can you show this?
I can prove angle EGH and GBC are equal but idk bout the rest
<GCB = <CGH = <GHE implies similarity
For CGH=GHE, GC must be parallel to EH
That can happen when EG and HC is the same (i used basic logic to figure ts out)
Or am i slow
true
Yeah but how is EG=HC🥀 there is literally nowhere in the question that implied this
so from this EGH is similar to GBC and you can just solve for m
triangles EGH, GHC share a side GH
Bruh how is eg=hc
leads to something called congruence
Yeah but they need to be similar first
And the CORRESPONDING sides needs to be equal
yeah
How EGH and GHC similar and how does that make EH parallel to GC
ok nvm about the how does eh parallel to gc part
I get it
But how is egh and ghc similar
<CGH = <HED = < GHE (because of our original pair of parallel lines) directly imply EH // GC
oops
Just say the question is impossible bruh the mofo writing this book (sukino) made at least 40 unsolvable questions in this book💔
its not
Ok
plus youre doing extra harder things instead of solving this question
we only need EGH and GBC similar to find m
Ik but there is literally no way we can make these 2 triangles similar we've gone through this
???
i literally just told-
Bruh am i slow or sum💔
FOR THAT TO HAPPEN EH AND GC MUST BE PARALLEL WHICH MEANS EG AND HC MUST BE THE SAME LENGTH
combined with <EGH = <GBC that you found
Cro🥀
what makes you think they cant?
they maybe are but we need to prove it to use it
also what i said doesnt use those two facts you listed at all
so we dont need to prove that ,theyre just implications from this
uh one second
oh wait
yh mb bro
ts horribly constucted i think
we have <BGC = < GCH
Dw bro i can read it
ignore what i wrote in red i dont think its right
k
what book is this even from bro
Yeah bruh i literally think we're just wasting time together here
You keep saying that CGH=GHE even though for that to happen GC MUST BE PARALLEL WITH EH, also forgot about eg=hc so gc parallel to hc since that's completely wrong, and bruh i hope you realize the only reason gcb=cgh is cuz gh and bc are parallel💔
Imma just close it here
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yea vro
there arent official solutions at the back or something??
or online
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Nah the no solution in the back and no solutions online
There is a qr code to the answers page but it's literally broken sob
Like even my strongest technique "the way of staring" didn't work😭
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You assumed $x\in A\setminus B$?
Buzzing Hornet
Let's not mock helpees
Sorry
I'll focus
@tacit jacinth so the thing is
why did you assume?
and once you've defined x is an element of $A\setminus B$
Licht
Anyway Licht is right in that this is sort of a mess, it doesn't really follow any of the proof structures you've presumably been taught
It might be a good idea to think very carefully about the overall structure of your argument
you cant furthermore tamper the definition of x, other than directly deriving it from the way you've defined x
Its like saying you have two dads
sorry💀
Unless, I'm missing something, we shouldn't even be starting with this
Yeah
In what way?
no no dont misunderstand me
if you define x twice
thats what my analogy referred to
And why's that like having two dads?
biological of course
because biologically you can have only one
Sorry about that! Anyways, at this stage you should be thinking explicitly about questions like "Am I using proof by contradiction" or "Am I using proof by contrapositive"
no wait, either way he made one assumption which he didnt even use
My point is that he's starting in the wrong place
Thinking about these kinds of things will at least avoid starting one's proof with "let x be in A setminus B"
youre doing it like assume all girls are not blonde. Now we asume the sky is brown. But the sky is blue. hence all girls are blonde
it still isnt
Hmm? what's wrong with this proof?
Then wtf does "it still isn't" mean lol
Anyways yeah I think you've got it, if you don't have further questions you can close the channel
It's a little messily written but I don't see any mathematical errors
Minor actual quibble is that "x in A and x not in B" is redundant, you only need one, and in fact in part two you only say one
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@silent pumice I don't accept dms, but you can ask your question here- this channel is yours now, ping me when your question is resolved.
@late sinew Has your question been resolved?
this channel is now mine
Lel imma close it seems like they're afk
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Can I ask how does d/dx(ln y) = 1/y * dy/dx? I dont get how dy/dx spawns out of no where
Its in terms of x
So really lny is ln(f(x))
So following the chain rule you have 1/y multiplied by the derivative of y with respect to x
I understand this but dont understand why is it dy/dx
(f(g(x))'=f'(g(x))g'(x)
D_x[fog]=D_g[f]D_x[g]
dy/dx=dy/dg dg/dx
I understand the last line but not the first 2 libes
You take the derivative of the outer function times the derivative of thd inner function
The first two lines is chain rule
And the derivative of y is dy/dx
same thing in 3 different notations
fog is the composition of f with g
try using 3 notations with a simple example
like
$$e^{\sin x}$$
gfauxpas
Wait but differentiation haven't started
But what happends next
i mean to differentiate e^y wrt x
ill.do the second notation
D_x[e^y]=D_y[e^y] D_x[y]
your turn, do the first notation
Give me abit im trying to process
np
on the rhs or lhs?
what is the derivative wrt x of e^sin x? forbet the notation for a moment ,whats the answer?
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Both
But rest has one dy
Which somewhat violates my understanding on the equal sign
Derivative of that hmmm, tbh I haven't learnt that
Oh
But its still something that spawns out of nowhere
its part of Dx
Oh
like in
Wait I'm abit confused
dy/dx=dy/dg dg/dx
Because tbh I haven't learn anything about logorithmic calculus
I just searched it up today
nothing to do with logs
I see
Oh yes
ahyway you need to learn how to differentiate
d/dx e^sin x
i have to go now though
Sorry but is it possible if you do it step by step so I can see hehe...
Oh I will try
So e^sinx
d/dx[e^y]=d/dy[e^y]d/dx[y]
Okiee thanks
@mystic saffron Has your question been resolved?
e^sin x
d/dx (e^sin x)
= -cos x e^(sin x)?
But i dont know how does this relate to the chain rule, is this even correct? TAT
i think you differentiated sinx incorrectly
also the chain rule states that (fg)'=(f'g)(g')
if we let f(x)=e^x
we get that e^(g(x))=e^(g(x))g'(x)
so the e^g(x) rule is just a special case of the chain rule (where f(x)=e^x)
I see
But but what is it that i did incorrectly
what's the derivative of sinx
-cosx
@mystic saffron Has your question been resolved?
Oh damn
I thought it was always flipped signs
Im self studying, preparing for my first semester
So kinda tusty
rusty
HAHAHA
But thanksss
gl
and rmb to close the channel if u don't have other qs
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$x^4-8x^2+1=0$
Tan
$\sqrt$
Tan
backslash
use $\sqrt{}$ 
Frances
HAHAHAHAH
uhm
so x^2=√4+√15
i dont get it
whered the root 4 come from
huh
$y=4\pm\sqrt{15}$, so $x^2=4\pm\sqrt{15}$ is what you mean?
;(
$\sqrt{4\pm\sqrt{15}}$
Tan
yes
Oh, ok
so x would be this right

Well, with another plus minus, yes
You can simplify it; I don’t think it is too hard (don’t trust me, I haven’t tried it yet)
you can simplify this
so it just gives decimal answers 
skul
well then you dont even bother simplifying
just toss that shit into your calculator or w/e
calc bashing time
Just put it into a calculator 
or WA
i did
8 + 2root(15) = (root(5) + root(3) )^2
.
well i dont think they would expect you to calculate that so
just give it in the exact form
,w solve \sqrt{4\pm\sqrt{15}}
im pretty sure they do
cuz in my textbook
uhm
i mean it is possible to calculate square roots to a certain accuracy
^
but its quite tedious
should i just write down this
just the answers
hmm
on exams, i think they would either allow calcs and ask you to round or just say state exact answer
It isn’t too hard, like I said
just in case, lets say you want to calc sqrt 15
Just let $\sqrt{a}\pm\sqrt{b}=\sqrt{4\pm\sqrt{15}}$ and solve for $a$ and $b$
is it like $4+\sqrt{15}\\sqrt{16*15}$
Tan
ive heard this somewhere
;(
Not quite sure what you did there
multiply by 4
outside and inside the root
but somehow there is another 4 in the root
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How do i find the vertical asymptote for this equation
A video told me this but I wasn't sure
do you know where the VAs of just tan(x) are
uhh
and/or do you know what the graph of y=tan(x) looks like
its what makes tan 0
right?
oh
I know that the graph is like a bunch of lines going up
repeating
what is the definition of tan(x)?
y/x?
in terms of other trig functions
@indigo dirge can you take this over i gtg
yep sure
What is the definition?
do you know tangent in terms of sine and cosine
I don't think I do
yes
ok, so if sine is $\frac{O}{H}$, cosine is $\frac{A}{H}$, and tangent is $\frac{O}{A}$, what do you know about tangent
Frances
how would you manipulate the first two to get the third
you put the sine on the top and cosine on the bottom?
mhm
I dont understand what you mean by manipulate
can you express tan in terms of sin and cos given this? ^^
that makes tan?
express it in terms of O, A, H
that makes O/A
mhm!
oh is it because H is canceled out?
yes
so if the denom is cos(x), when is it 0?
in general
If you think about it when tan is sinx/cosx, there will be an asymptote when the denominator is 0 since its impossible to divide by 0
bc cos x has infinitely many roots (aka when it is 0)
you had it here ^^
oh
just generalize it
I don't really know how to generalize it
hint: it doesnt need to be in between 0 to 360
yes!
alr take a look at this
can you generalize the roots now?
hint: all roots are the same amount apart
pi/2 +k pi?
yes
I remember asking about the question but for sec
and someone said you have to add k E Z
ah well
this to restrict k to the integers bcz if k is something like 7.3 it would mess up the solution set
so it is only for certain questions?
If the the interval is given no need to find a k value
If not then restricting k to the integers is the correct way to do it
Because as I stated it’ll mess up the solution set
Like here if k is in R rather than Z then k can take a value like 917.528 and ofc it’s not in here
so for my question would it be neccessary to add the restriction?
Yes because given there is no interval
k should be in Z
im sorry but what is an interval
its just a range of numbers
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why do we only need to test the first floor(sqrt(p)) positive integers
(question-prove that 37 is prime)
a * b = n implies a or b is less than or equal to sqrt(n)
yes
why does that matter
that answers your question?
i still dont see it
what is it?
For all the pairs of factors of n,a and b, such that a*b=n, either a or b will be less than or equal to sqrt(n)
So like if we can't find any factors under sqrt(n) we know there aren't any pair of factors so the number is prime
oh so if both of those factors will always be less than root p floor the max possible value will be root p floor
if both a and b are $>\sqrt{n}$ then their product will also be greater than n
DaveyLovesSocks
am i right?
I mean a factor can be more than root p floor but then the other one will be less than root p floor
but how
its not possible its given
For all the pairs of factors at least one of the factors in the pair has to be less than floor(root p)
Like 10=5*2
floor(root 10)=3
5 is greater than 3
But 2 isn't
so the max possible value will always be root p floor?
I mean in a way
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I'm trying to understand my textbook, and some confirmation would be much appreciated. Suppose I have the differrence equation
$$g(k) = p g(k+1) + q g(k-1) + 1$$
where $p \ne q = 1 - p$. We notice the homogeneous case can be refactored to
$$\Delta g(k) = (q/p) \Delta g(k-1)$$
which has the general solution $\Delta g(k) = \alpha' + \beta' (q/p)^k$. We then notice the telescoping sum
$$g(k) = g(0) + \sum_{i=0}^{k-1} \Delta g(k) \equiv \gamma + \alpha k + \beta (q/p)^k$$
If we then try a particular linear solution, we see $k / (q-p)$ is a solution.
\par
My question: Can this particular solution \textbf{replace} the linear term of the general solution, or can it just be absorbed?
$$g(k) = \gamma + \frac{k}{q-p} + \beta (q/p)^k \qq{OR} g(k) = \gamma + \left( \frac{1}{q-p} + \alpha \right) k + \beta (q/p)^k$$
Shuba
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soft question
we say that a map F: X \to Y is proper if for every compact K in Y, its preimage F^-1(K) is compact in X
I'm curious as to why we call it that adjective
what is so "proper" about these maps, which aren't even necessarily continuous?
@pastel orbit Has your question been resolved?
why do we call an ideal ideal if theres nothing ideal about it
park in a driveway drive in a parkway
anyways this property seems to stand out.
A topological space is compact if and only if the map from that space to a single point is proper.
I'm not exactly sure why this gives it its name though 
thats like a very cool property
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What variables to replace here? a=b, or a=b+c does not work
what is the factor property
factor property is like if by replacing any variable a with any other variable b., the determinant becomes 0. then (a-b) is a factor of determinant
kind of self explanatory lol

better go for row column transformations, like try r1->r1-r2, etc
try to just make as many zeroes for easier expansion, i'd say
we are asked to use factor rule....
I just tried a=-b, I think it's working
the degree checks out, its gonna have 3 factors at max.
but it is quite absurd that they wanted us to solve it by such an unknown method
try a=-b
quite weird
and the symmetry is obv
so b+c and c+a are factors asw
write it as k(a+b)(b+c)(c+a)
now put a=b=c=1 in both sides, find k
should be 4
its not, infact it works better than row and column operation sometimes
a=-b is not working......
i never learnt it tbh. it always seemed as high staking and absurd, so i relied on row column transforms, and your point is valid too
same, no need to learn it. I just discovered it last year by accident while doing the triangle collinearity type shi and this year it's apparently a part of our syllabus
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how would you solve this using pigeonhole principle? i literally don't know where to start
(or any method really, we were just learning about pigeonhole)
You can first look at any two points of these 5 points. These two points define at least one great circle, so choose one of them
and then pigeonhole the remaining points
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[I think they uniquely define a great circle, except if they're polar opposites]
[but the rest of the argument still applies]
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hi
I got 2x-1 for [g o f]
not 2x + 1
im a lil confused
g(x) = 4x -2 + 4 / 2
4x - 2 / 2
2x - 1
-2+4 is -2? 

No i just figured it out
i have a question abt this one tho
would you say this is one to one
the only thing im confused abt is the origin
i cant tell if it passes the horizontal line test
@cobalt owl Has your question been resolved?
Hmm
This looks like an odd-degree function, no?
Of course, if you don’t have the exact function, you don’t know for sure if it’s one- to-one
though it appears to pass through (0,0) and (1,1), most logical guess is f(x)=x^3
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Hi I need help with drawing the reciprocal of these graphs I know its 1/f(x) but as I drew them they started looking wonky
for reference these are the graphs I got after
@candid sparrow Has your question been resolved?
@candid sparrow Has your question been resolved?

The others looks alright, but I would like to understand your view on why you drew this one the way you did
@candid sparrow Has your question been resolved?
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finding the s.a
i got 1392.7 when the answer is 1192.7
i dont know where i went wrong?
The SA of the cuboid is not what you think it is
what do umean?
I mean that while its TSA is what you have written, not all of it has to be included when calculating the SA of the entire shape
tsa means total surfacea rea?
Yes
also, i got the answer, but i dont understand why
from my equation in the pic
i minus'd (20x10)
in the equation im sure i didnt double up on that already
Look at the shape carefully, there is one side of the cuboid that shouldn't be included
oh the one touching the cylinder
but like when calculating the s.a for the half cylinder
there wasnt any working for the rectangle of the half cylinder
Why do you need to include that rectangle?
oh wait im so dumb
Its inside the shape so it shouldn't be counted as surface area
ur right
its internall
damn i understand
thanks bro
i been thinking of these problems in parts lol
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what did I do wrong
hi hell
helloo
,w 100 - 80x + 12x^2 = 0
i got a correct
yup
it seems u've solved it incorrectly
oh damn
,w (x - 10/3)^2 = 25/9
shouldve kept the negatiev sign
,calc -80 + 24(5/3)
Result:
-40
u need to use the original eq to find hte volume
other than that and the current one, nah
@shrewd trellis Has your question been resolved?
@shrewd trellis Has your question been resolved?
From what I can see, you found the second derivative, plugged in your answer of 5/3 into that and then substituted that result into the first derivative, incorrectly
Which is not what you're meant to do
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Given AB=8 CD=5 BP=6 and angle APD being 60°, find the square of radius of the circle
I forgot the chord theorems or whatevs its called
power of points?
PB * PA = PC * PD
if I construct line AD, would it form a right angle triangle?
Hello everyone! i am new here
not unless you prove it must be, no
why do you think it would be?
looks close enough
guys of what class this question is?
idk man im just doing this for fun
yeah you cant just do that lol
can anyone help me with this
!occupied
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please use an open channel
@ashen hatch Has your question been resolved?
@ashen hatch Has your question been resolved?
4²+a²=2.5²+b²
10²+a²=(x+2.5)²+b²
you can get x from here then use it to get r
@ashen hatch
this looks correct to me, tell me if you see anything wrong with this
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yo
what are you doing in those last three lines
Long time no see
i forgot about the right side
😂😂
damn been a while
this is for my uni entrance exam
oh, that third last line was two separate steps
wait let me try and fix it
you multiplied by half instead of dividing by half
yup
yea i havent solved math for a while and forgot 1/0.5 is just 2
made it way easier
thanks
how do i close
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While reading a book in Linear Algebra, I noticed this passage:
A dot product between a vector and a vector space.
Questions:
- Is that common notation, or is that particular to this author.
- I assume that means the following:
Have you personally seen that notation before, or is it new to you, as well?
there's a lot of similar instances
for example, $a + B = {a+b\mid b\in B}$
Raphaelisius Maximus MMIII
so it's natural to assume $\vec w \cdot S = {\vec w \cdot\vec v\mid \vec v \in S }$
Raphaelisius Maximus MMIII
Well, that latter I do understand. But, the result of that is a set, not a number.
The strictly proper would be this this, then?
that's correct
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i cant draw tgis
may u b my mth techer
Have you tried solving for the roots?
roots were 1 and 0
They are not
1 nd -0
You got the y-intersect correctly by substituting x=0 to the formula
Now substitute y = 0 to get x-intersects, i.e. the roots of the expression
What do you even try to get these answers?
i sued quadratic equation
i used calcualtor
i thnik clacluter uses quadrtic equation
calculaor said x1 and x2, 1 -0 respectively
How did you use the calculator
Because it's wrong
You know that you need to rearrange the formula to
-x^2 + 4x -5 to get the correct answer?
The solutions are
2 - i and 2 + i
Which means they are complex solutions i.e they don't touch the x-axis
oh
You're supposed to use the derivate.
i shud first use discrminant
huh
I don't think so
Using the derivative won't help that much in sketching the original function
At least you get the max point, I guess that helps.
it does aha
You're just sketching the function, other than that doesn't matter.
did u see mty sketch'
its so difficult
scheme said shape down coz -1 and use y intecept
Sketching function is to be honest substituting values, plotting points and then connects them.
turning point, x intercept, y intercept
Make a table for, say -2 -1 0 1 2, then you pretty much good to go (or find the critical informations, intercept and max/min point).
The final 2 thing you can do are
1- get the turning point of the parabola and sketch it
Because the co-effecient of x^2 is negative then it would be the max point
2- substitute different values of x and sketch them on the graph
..
.
Where's your table?
@tame echo Has your question been resolved?
i thought..what about using turning point, y intercept and x intercepts if they exist, you mean they will automatically be there?
when i use table
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hello :3
i am trying to find a 3d point between two other 3d points, and the rotation to align an object along the line the two points make
i'd perfer a set of euler angles, but a straight answer for quaternions would work too.
@gray hearth Has your question been resolved?
Line from x to y will have direction of y-x, as a vector
Just normalize it and apply formulas to calculate pitch/roll/yaw, they should be easy to find online
that doesnt really explain much and everything im finding online isnt in the right format for what i need,
what format do you need though
the vector direction x-y is the same, regardless of your axes. the pitch, yaw, and roll depend entirely on how you set up the axis.
are you trying to find the midpoint between two other points in a 3d space?
again, it depends on what axis you're using
ok let me rephrase my question
Moreover, you can't totally define a rotation by one vector, you need the forward and upward vectors.
i want the x, y, and z rotation that points from the origin to another point
there's an infinite number of these vectors - consider a plane pointing in that direction whose roll is undefined.
you need an "up" vector as well.
"up" is my Y Axis
Let $v = p_1 - p_2$ be your forward vector, and $y$ be the y-axis (your upward vector).
\begin{enumerate}
\item Normalise the forward vector
$$z = \frac{v}{|v|}$$
\item Compute the right vector
$$x = \frac{y \times z}{|y \times z|}$$
\item Compute the corrected upward vector
$$y = z \times x$$
\end{enumerate}
Now $(x,y,z)$ is your rotation matrix. Notice this only works if your forward vector isn't the y axis (i.e. the player isn't looking directly upwards)
so then how do those translate into rotations?
Shuba
do those numbers represent values between 0-360?
like am i getting degs? rads?
something else?
(x,y,z) is the rotation matrix. Take any point p, and (x,y,z) p is your point rotated in the direction of the forward vector v.
ok
and |v| means normalizing not absolute value?
$$|v| = \sqrt{v_x^2 + v_y^2 + v_z^2}$$


