#help-36
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Also, thank you so much for taking your time with me, this is helping me a lot
What do you mean to the dimensions and not to the areas?
Firstly calculate cross-sectional areas (according to the given dimensions) and then use the modular ratio
and not the other way around
this?
Yeah, basically area of the rectangle
So like 12x100x2, 375x12
Yes, so this is for steel channel
and for wood it would be 375x88
so 351x12 for here too?
My bad, i thought 375 was the full width
No, because this for the steel channel
oh yeah true
Can you determine where the centers of gravity of these rectangles are? (You need to assume some origin for reference)
What do you mean?
I think it's the middle of each
because it wasn't specified in the question
So, now I have to find y1 through 4
Yep
Half of the width of y1? So 6mm?
175.5
Correct
- 12
44 + 12, because we have to include the bottom flange
y2 is 6 mm, and y4 is 56 mm
All in all:
y1 = y3 = 50 mm
y2 = 6 mm
y4 = 56 mm, right?
Now, use this formula
Remember that for wood you are supposed to apply the modular ratio (for A4)
ok one sec, ill send the picture in a second
Like this? I added the red after cause idrk
Did you multiplied it by at the top and the bottom or...?
And it should be divided by 16.67 not multiplied, because A4' = A4/n
Now I'm confused again- why are we dividing?
We want an equivalent section made entirely of steel
it's as if we were transforming wood into steel
It's correct, but you should divide
Good, last thing is that A4 is 375 * 88 = 33000
Because 375 is already the width of wood
ah- i think i did 351, mb
Quick question, if I say y bar instead of c, would it still be correct?
Yes, it's just notation
ah ok ty
because i need to take c away from something, right?
moment of inertia equation, right?
Yes, it's basically parallel axis theorem (Steiner)
I know that the numbers are wrong, but it's basically this, right?
I get AD, but the I section, I'm mildly confused
You mean for the bottom plate?
You know the formula for the moment of inertia of a rectangle?
Let me try to find it
OH
ok now that makes sense
Good lord, you..are saving me right now
But yeah, for the bottom plate, how do I go about doing that part?
e.g. for A1:
I1 = 12 * 100^3/12 + 1200 * (50 - 29)^2
for the bottom plate:
b = 375 mm (width)
h = 12 mm (height)
A2 = 4500
I = 375 * 12^3/12 * 4500 * (6 - 29)^2
a3 = a1
And for A4... we are supposed to apply the modular ratio
So basically, we can just plug A4' or however you denote it
And additionally divide I4 by n I guess
A4' = 33000/16.667
?
Yes
then Itr, I just add everything together?
So I4 = (375 * 88^3)/(12 * 16.67) + 33000/16.67 * (56-29)^2
Yes, Itr is the equivalent moment of inertia
For the transformed system
Then for the maximum stresses, I just insert all the letters in
Wait, before that, I have to actually find c
Yes, for steel you can use ȳ
I mean c = ȳ (for steel)
And for wood
The maximum stress will occur at the point furthest from the neutral axis
Of course substituting 29.04 for 33.15, they said 112, I'm guessing it's just 100?
Thank you SO MUCH
I spent a whole day searching it up online, I got nothing from anything, thank you so much <3
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any thoughts?
do I need to check every axiom 1-10?
yep, generally you do, unless you're working with a subset of something that's already known to be a vector space
okay yeah we learned about subsets today and I remember learning something like that
in the case of the real numbers, for many of the axioms, you can probably just say "this holds because the property holds for real numbers"
e.g. you don't have to prove that addition of real numbers is associative
yeah like this one axioms 1-3 I just did let u = 1, v = 2, w = 3
like what's the point in doing that is it not just obvious?
I'm honestly so new to the topic this is the first problem I tried solving
for the real numbers, most/all of them will be fairly obvious and will result directly from the fact that R is a field
hmm okay
do any of these seem more difficult? perhaps I can try one that's harder and you check my work?
do you have any thoughts on 8?
hmm
well standard addition and multiplication so that's easy enough
maybe the multiplication stuff will end up weird?
<@&268886789983436800>
check whether it's closed under addition and scalar multiplication
"closed" gets mentioned a lot, what does it mean?
axioms 1 and 6
as in equal?
no...
axiom 1 can be paraphrased as "V is closed under addition"
just means that the sum of two members of V is in V
"closed" generally means that you do some thing (i.e. here, add two elements from the set) and the result is again in the set
try reasoning without writing stuff down
(until you want to write a formal answer)
is the sum of two invertible matrices invertible?
how about the product of a scalar with an invertible matrix?
that is as well
sadly both are false
LOL no way
what if the scalar is zero, for example
oh, right
and what if you add A and -A
haha that's why i suggested this one, it's not as obvious as the real numbers example
okay so 1 and 6 don't work so is there even any reason to check the other ones?
oh another quick thing to check, always
a vector space has to contain the additive identity, which would be the zero matrix for matrix addition
but the zero matrix is not invertible
jeez, these are all words I've heard in lecture but they just didn't click
nw, they'll click a lot more after you do more examples
do you suggest I try to do more problems or like watch videos or read up on the topic?
try problems, i think it's the best way to learn
i know it's tedious going through ten axioms but it's useful
(at least while you're first learning)
okay for sure
I'll make note of everything you said and try some more problems, thanks for the help
sure, feel free to ask here if you want to check your answers or if you get stuck
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Is there any easy way to solve this???
trig ratios?
easiest way is to use trigo
Yeah but idk how to solve jt
okay so do u know any trigo identities?
Uhh no??
okay so when we refer to basic trigonometry, its often explained in terms of right angled triangles
so when u have a right angle triangle with one of the non 90degree angles as theta
u can use that to determine other angles and sides
there are three fundamental (actually six but these r the basic three) identites
Ah sin cos tan?
yes
Use change of subject with sin cos tan
u can just use sinθ = opposite/hypotenuse
@wispy shore Has your question been resolved?
Ok
you can use calculator?
Yeah the t1 84
bruh idt u need a calci
i wish you can understand it
its just a question, i dont need it
u overcomplicated it bro
its just sinθ= opp/hyp
so sin30=5/c
c= 5/sin30
so c =10
Speaking of which, just use the answers from the parts in the Pythagorean theorem
yeah, that's correct but not the only way, maybe he doesnt know bout tan or idk
i only use sin, i think its easier... for me
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I dont even understand the question, what shud i do for i and ii?
for i, I sub x =10?
for i, they want you to find when the investement will increase, so when the function is increasing
specifically in the first 10 years
oh
is this 12board sample paper
no
can you solve the problem now?
ye
what abt ii?
its increasing in (-inf,3) and (5,inf)
i think lean patch would refer to a period of poor performance
so when the investement is decreasing
okay so where is it increasing between 0 and 10
then its (3,5)
(0,3) and (5,10)
ok cool, thanks for helping
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What part are you stuck?
Hmmm
I am not technically a helper but i have some ideas on how to solve this
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
anyone helps is helper
@neat wolf Has your question been resolved?
I have simplified it a bit but I may need a fresh perspective to go on
Please note that it all equals zero at the end
If anyone has difficulty understanding what I wrote, please ping me
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Hi there, when using rules of logical equivalence to derive if its a tautology, contradiction, or contingency, how do we know if its a contingency?
cause for tautology and contradiction, you just need to see if the truth value after deriving is either T or F
isn't a contingency just a statement that is neither a tautology nor a contradiction?
<@&268886789983436800>
yeah
but we're using rules of logical equivalence (de morgans, associative etc etc) here instead of using truth tables
oh sorry, missed that part
the truth tables should be proof that its either a contingency, tautology and contradiction in my worksheet
i acc asked this because im confused
on this part
((p v q) ^ r) <-> (p v (q ^ r))
heres my solution for now
truth table says its a contingency
are you asking how we can easily read off from some formula after doing some rules of equivalence whether the formula is a contingency or not?
if yes then this is just strictly not possible cause its basically the SAT problem
which is famously very hard
otherwise I'm not sure what you mean by your question
i guess its this one
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Can somebody check this for me specifically 10 a
whoa there. so 3sin(theta) = -3, which gives sin(theta) = -1. where did the sqrt(2) come from?
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?
Special right triangles
what made you think I'm here to ask a question lol
that does not explain what gave you the right to stick a sqrt(2) to the value of sin(theta)
??
that changes the question
Because six is y/r
should we revisit the unit circle definition of sin and cos
it might be necessary here
I don’t know how else I would solve the problem because I would not know the radius or any other side lengths
what's y and r supposed to mean?
Uhh I think opposite and hyp I can’t spell that full word
have you gotten a simplified expression for sin(x)?
I think
what did you get
Sin(O) = -1
In my teachers answer key for a different homework but same problems we use the special right triangles
mhm
and which angles satisfy that equation?
uh do you know the unit circle definition of sin and cos
,rccw
huh
The angle values? I think
looks like you don't understand the unit circle definition completely
I mean this is how we did it with other similar problems in clsss
say, there is a circle of radius 1
its not a special triangle this time
plus, do you want to rely on only one tool to do the job?
how would we know? Like how would I know a test
My teacher said not to use the unit circle right now
Like we haven’t done it at all this year
don't listen to them
teaching trigonometry without the unit circle is the same as teaching how to run without teaching how to walk
I mean I kinda have to for the test and this is the way I know
ok continuing from here
this circle has a center, of course yes
now, if we chose a random point on the circle
say, 45 degrees, and draw a line from the center to that point
we then get coordinates
I just don’t know how to do that I did it some last year and I can’t really learn it now because my test is in a little over a hour
And I don’t have the unit circle memeorized
.... THERE IS ZERO MEMORIZATION INVOLVED
I just don’t know if I can learn a new method 😭 and be confident with it
see this diagram?
there exists a x and y coordinate for the random point selected
say, there is theta2
theta 2 is labeled a bit badly but you get the picture
can you determine the sign (positive or negative) of the (x,y) coordinates?
what a bad take
I mean I find it easier tbh
I also know she adjusted the unit slightly because none of us really learned square square roots well. Like we know the basics but nothing beyond that because of Covid. Idk if that’s related
Not without any side lengths or angels
say theta2 is between 180 and 270 degrees
what would be the sign of (x,y)
I don’t know
answer: -x, -y
That would be quarter 3 so x and y would be negative
going back to this
It would be defintly in quarter 4 at least
in a unit circle of radius 1, if the center is at (0,0) what can you infer?
And maybe quarter 3
cos = x values of an angle
sin = y values of an angle
Because q3 and 4 is when y is negative
consider watching youtube videos on this topic
Wait why am I wrong
eh i worded the question a bit badly
the answer is that it can be in quadrant 3 only
assuming 180 and 270 aren't counted as 2nd and 4th quadrant
its not enough time to introduce a new topic sadly
I’m just trying to figure out which special right triangle it is because I realized the 45 45 doesn’t work
Wait
the special triangle is a 0 degree triangle
in this case
Is this correct
correct
Yay
Our limit is this
its kay then
domain is the word
yea
@static oak Has your question been resolved?
hey, might wanna close this before you open a new one @static oak
Whoops thought it was closed and clicked x instead of the checkmark I’ll just send it here
I’m not sure why I got this wrong. I know sin starts at the midline at the start of the period then moves up unless it is reflected over the x axis. But my teacher started with going down at the start of the period
<@&268886789983436800>
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can you help me graph this function with absolute value
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
1
not really
im bad at maths clearly
so do you know how to graph x^2
yes like a U
yes yes correct
so (x-1)^2 is translating the graph 1 unit to the right
the x^2 graph i mean
okay
and (x-1)^2-1 is translating this graph down one unit
think of it like every x value is pushed back by one so they need to compensate by going one more unit to the right
so that means everything moves to the right
ohh okayy
so you know how to graph x^2-2x now
yes
mhm
so it will flip every negative to the positive
the positive stay unchanged ofcourse
so the part that is negative is reflected through the x-axis
yep yep
so -|x^2-2x| now turns all of our value negative
so it flips it
yes
so after that adding three means the graph goes up by 3 units
yes
this is the final result
thats basically it
so thats it i dont need no formula or anything
okay bet
this is graph transformation, so yes, no formula
thank you man
alr np
!done btw
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huh??
clearly |A|max = 27
how is it so clear here
hadamard's inequality 
or just vibe it cause jee lol

once again diving into actual matrix knowledge thats conveniently gatekept from me
avg jee shit
either some forbidden knowledge or whatever this is
most reasonable direction i can try for this question is to assume the rows to be vectors lying on x + y + z = 3 and try maximizing the volume bound by the vectors
and in this case somehow volume is maximized when the vectors are orthogonal to one another
im not even going to
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thanks for the help though
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the greyed out parts are the ones I currently have selected
I believe those 2 are correct
I think the second and third down from the top are wrong
but it's not a combination of the second/third from the bottom with the top and bottom ones
so I must be doing something wrong
right
5th is off
its indefinite integration
5th is second from bottom
right
oh i mean 6th

2nd is intimidating
hm.. they did not define v
doesnt really matter
ok ig
I'm just tired of calc 2 and I'm only a week in 😔
why
the problem is that as a function $\sin: \R \to [-1,1]$
and defining arcsin as its inverse we have
$\arcsin : [-1,1] \to \R$
So inputs that surpass 1 dont make much sense.
but anyways, numerically its logical
idk I just want to actually get this homework done because I'm trying to start the year off by not just checking the TeX code for answers
because that works and it means I don't spend 6 hours on a homework assignment but the class is graded 90% quizzes and exams
so I gotta know the stuff
right
also, 5th was correct too right?
remember chain rule
what flaw do you see
no, 5th was plainly right
tbh if you dont recall chain rule youre gonna be struggling a lot.
ikr
its arguably the most important
yeah
please kill me
bro im 9th grade tf is this
i thought
ah
go to #❓how-to-get-help
if you're looking for help
you'll learn in calculus one
they are called integrals / antiderivatives
you too
you will die one day
thanks for reminding e
realistically soon too, you have less than 30,000 days left
(probably)
anyways
a little morbid
😭
ohhh the chain rule is easy
I just needed a refresher
been a bit over a month since calc 1
so am trying to get back into math mind
:)
life's short
do math I guess
aight, so, chain rule
dx/dy = dx/dt times dt/dy
plus the other parts of chain rule
but idk what exactly that does here
y'know
eh i just do subsitution then again
I guess I could just go to to office hours
OH
yeah
Idk why i didn't even think of that
that was stupid of me
substitution
is like the first thing to try
?
ln(x)=t
I'm used to using u
but yeah
alr alr
lemme cook (then get confused) and will report back when I get it wrong
alr so integration of ln(u)/u times du
i believe integration is the right word lol
summation is like E
brain is fried currently, this is hour 5 on this assignment
yep
you right
it's the diagonal lookin E
anyways
hm
I can integate ln(u)
m side way$\sum$
scoob
I just don't exactly know what to do with the u in the denominator
what
ln(u)=p
ye substitute thesubstitution
wha
then dp= 1/u*du
layered substitution
so then you get p
i hope this violates nothing tho
what do u mean
nothing
We just have no money for student math tutors because of budget cuts so
:P
here I am
it doesnt
fuckin Ohio
since we’re not defining bounds anyways
is the integration of p times dp just p
or is it p^2
I'm pretty sure it's just p
well
but just wanna check
whats the integral of xdx
er
damn
no
I'm cooked
@oblique estuary what are you currently studying ?
i wanted to see first if it was the letter tripping you up lol
ohhh x_C
anyways
+C
still no
first week of Calc 2
is that in cllg ?
this is supposed to be a review homework
yes
so yk how antidifferentiation (integration ish) is the opposite of derivatives right?
right
lets rev for a sec
we did that
whats the derivative of x
1
okay sick
when we integrate 1dx what we get
💀
x
ur chill np
sick
so when we integrate xdx
we’re asking
what do we differentiate to get x
.5x^2
x^2*
peak
what we get on differentiating x^2 not x
i said what do we differentiate to get x
wait mb i forgot to read to
real
LOL
illiterate gang
chill guys
shttt i might have Dyslexia
oh so it's just .5p^2
yall good here...
ye
I think
then just undo the substitutions one by one
lmao
she thinks...
one braincell
we chill here
can i see the problem?
$$\int\frac{\ln\ln x}{x\ln x} \dd x$$
oops
blanketism
yo tf you mean illiteracy
aight
yo
not literate
since when is knowing english equivalent to litereacy
@marsh mountain
when englanders colonized most people
ANYWAYS
did they perhaps want fractions?
that should be the answer
no
you can use the texit bot by writing latex then enclosing it in inline/display delims
blanke q is lost pin it
fwiw, you remember how you were asking about chain rule?
knowing a language isnt equivalent to litereacy , most chinese cant speak english so based off ur def they are illeterate ?
you couldve done this problem with one substitution, u = ln(ln x)
brother there is lnx below too
differentiate it?
got the second part
yea mb that works
ahhh
anyways
that's what I must have been meant to do
yeah
instead of layered substituition
yep
I mean layered substition isn't review for me
I've not ever been taught it in class
but it's literally just
substitution
so it's fine
easy stuff
I got the second part done easy cuz it's just plug and chug of part one
yep
I have 3 questions left but I'm gonna go to my prof's office hours
since I have a bunch of other questions relating to other stuff
she wants us using this AI thingy that I opted out of because I didn't want to be a part of a research study
it's not supposed to affect our grade though opting out of the study
so I'm gonna ask her
good luck!
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you too!
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Hello, I need help with trying to prove an equation from James Stewart's Review of Algebra
First, I'm gonna show the documentation because it's available for free on the james stewart website
So, in this file there's a thing called the Distribution Law
Actually it's Distributive Law, my bad
The file says that if we use the distributive law three times, we get this result:
The thing is, how I would use the Distributive Law three times by myself? I'm really confused on this part. If I just keep multiplying the letter A with (b + c) three times, it doesn't get the result from the text book. I got a^4b + a^4c, which makes no sense.
a, b, and c here are any terms, they dont need to be the variables a, b, c themselves
for example that law can be used to show that
4(3 + 5) = 4*3 + 4*5
or that (a+b)(c+d) = (a+b)c + (a+b)d
in the second case, the "a" in the distributive law is (a+b), the "b" is c and the "c" is d
look at the color coding here
red(blue + green) = red*blue + red*green
its the same law in both cases, although it uses slightly different letters / terms
if i wanted to use the distributive law two times instead of three, how it would look like? using the letter terms
this is what we got after one application
now the 2 other applications are used to expand (a+b)c and (a+b)d
you technically need commutativity as well, to convert it to
c(a+b) and d(a+b)
but now, you can expand it using distributivity
note that the terms circled in purple are the same
i can expand c(a+b) usind distributive law to ca + cb
then i can similarly expand d(a+b) to da + db
that's 2 other applications of the distributive law
so (a+b)(c+d) = (a+b)c + (a+b)d (Applying distributivity here)
= c(a+b) + d(a+b) (Commutativity)
= ac + bc + d(a+b) (Applying distributive law on c(a+b))
= ac + bc + da + db (Applying distributive law on d(a+b))
so total of 3 applications of the law get us to the result
- 2 minor applications of commutativity
yeah commutativity is key here
the most important thing to realize when reading laws like this one is that a, b and c dont have to be just the letters a, b, c
if any expression is of the pattern
something1(something2 + something3)
you can make it
something1 * something2 + something1 * something3
it doesnt matter what something1, something2 and something3 are
the only thing that matters is the pattern
# (# + #)
yes, that's why flowchart diagrams can be helpful for this
@cinder galleon Has your question been resolved?
i'm trying to understand 😭
idk what to choose
i can do this with numbers but it gets abstract with letters
# (# + #)
you need to spot a pattern like this basically
or (# + #) #
it'll be clear once you do enough exercises
I actually did the review exercises, but i'm trying to prove it on the letters to see if this makes me better at math
I think it's called the proving method I think
Basically you prove the equations on the book to make sure you know it?
yeah, ig thats a good way to learn it, but maybe it would be worth it to try it with slightly simpler combinations of letters first
and not with that double parenthesis (a+b)(c+d) thing
when i see something like x (y + z) i multiply the X with Y and Z, so it would result in xy + xz
yep, thats how it works
and when you see
(a+b)(y+z), you can just interpret (a+b) to be ur x and do the same
(a+b)y + (a+b)z
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We consider positive integers of the form
$$
aabb = 1000a + 100a + 10b + b,
$$
where $$a \ne 0$$ and $$a, b$$ are digits.
(a) Prove that every integer that can be written in the above form
is a multiple of $$11$$.
(b) Determine all integers of the above form that are multiples of
$$4$$ and $$9$$, and write each of them as a product of prime factors.
ponkur
which part are you working on
well actually i will disappear for a little bit. if the first part, just try to write aabb as 11k for some integer k. if the second part, maybe look at multiples of 4 and 9 and figure out what they “look like”
@slate anchor Has your question been resolved?
the b
ik how to get nummber weith can multiplye with 4,9
just the whole b
i need some help i got the a pretty easily
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Before we even focus on the asymptotes im trying to get the domain
I set the denom != 0 and tried to solve but got stuck
sqrt(x^2 + 3x) != -x
x^2 + 3x != x^2
Then one of the terms dissapears
3x != x^2 - x^2
3x != 0
So we just have x != 0 which cant be right
We need 2 values for x
So what did I do wrong?
well lets just say, when do we have 1/0?
When the denom = 0
Which is why I tried this
But ya idk what I did wrong
there is another condition for the domain
the inside of the square root cannot be negative
I dont think it was at any point in my work right?
Unless you mean squaring the -x to turn it into x^2
setting the denominator to 0 helps to find vertical asymptotes
But there should be another right?
but there can be other reasons why a region of the x axis is excluded from the domain, one of which is square roots of negatives
Cause the highest value of the denom is x^2
yeah it's like olivas said
that x^2 is inside a square root, so the highest degree is not that
check x^2+3x >= 0
close, but you're mixing the sign
Wait how sry
x^2 + 3x >= 0
x + 3 >= 0
you can't divide by x
use the fact that ab is positive when a,b are both positive, or both negative
it should be x =< -3
if x is between -3 and 0, x is negative, but (x+3) is positive, so x(x+3) is negative, and we can't have that
for both x and (x+3) to be negative, x=< -3
Wait first before any of that why cant I divide by x sorry
because dividing by a negative flips the direction of the inequality
but dividing by a positive doesn't
you don't know if x is positive or negative
How do we know (x+3) is positive sry
Alright I understand your point now
Ok I get it
Thank you so much guys!!!
❤️
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is the reason we need to have A intersect U not be empty as they said at the bottom is because it would make the above definition vacuously true if it were empty?
U cap A \ x_0 cannot be empty since x_0 is defined as a limit point
yeah
Then what is it ?
i’m saying do we define x0 to be a limit point to prevent the definition at the top from being vacuously true
Yes
ok thx
One of the reason the convention is this way i think is because you want to use limits to carracterise topological properties sometimes
But ye just suppressing the useless case is also good in general i guess
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hello
Asking the actual question right away is more likely to get responses.
Asking "Can I ask...?" or "Does anyone know about...?" doesn't give people enough information to decide whether they can help, and answering can feel like a promise to help with the actual question, which they might find themselves unable to.
@halcyon knot Has your question been resolved?
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<@&268886789983436800> troll
Don't troll here
@pallid sentinel pls do not troll
mod party
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free robux scam in bio too.
good catch thanks
no problemo.
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how to solve this?
check the minimum and maximum values for the lhs and rhs
why?
obviously you cant solve for x and y normally
so its gonna be some trick like that
but check the minimum and maximum values and see what you get
not exactly
sorry maximum
yea
can you solve for x and y now
do you know the formula for acos x + b sin x
of range?
no just like a kind of simplification
no
ok so let $a = r cos y$ and $b = r sin y$
CherryMan
then $a \cos x + b \sin x = r \cos y \cos x + r \sin y \sin x$
CherryMan
$= r cos(x-y)$
CherryMan
if we solve for r and y we get $r = \sqrt(a^2+b^2)$ and $y = \arctan (\frac{b}{a})$
CherryMan
so in the end $a \cos x + b \sin x = \sqrt{a^2+b^2}\cos(x - \arctan(\frac{b}{a}))$
CherryMan
did you understand the process?
yea
so if we want to solve for this we need $\cos(x-\arctan(\frac{12}{5})) = 1$
CherryMan
yea
that means the argument is (2n+1)pi
but if we just take one solution where the argument is 0
yea
then we get $x=\arctan(\frac{12}{5})$
CherryMan
thankssss
welcome
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Can someone help here
I saw someone said that angle EAF is 15
So angle ECF is 30
But im just confused how they knew it was 30?
,rccw