#help-27
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@finite gale Has your question been resolved?
Prove that triangle JMN is similar to triangle MNL
If you can prove this
The question can be solved immediately
how
im sorry im not understanding
Hmmm
What is the total amount of angle in a triangle
Answer this first
Then explain what is similarity in geometry
This is the 2 material we are going to use to solve this question
180
Between the two triangles? They both have right angle
No
Simmiliarity is when the shape have same angle but one is the enlargement of other
The similarity test in a triangle is if 2 triangles have 2 same angles then they are similar
If a triangle has angle 90, x what is the value of the third angle
90-x?
LMN = X, MNL = 90, we already prove that our triangle is similiar
Do you understand about similarity or should I explain it
@finite gale
Sorry for the late responses, im tryna do smth rn
Explain a lil more
We know that the smaller triangle have side of 15,8,17
Remember the smaller triangle have base of 8 cm
While the larger triangle have base length of 15
Remember similiar triangle is just a enlargement of the same triangle
So
8*x = 15
Find x and now multiply 15*x and add it by 8 that is the answer
Draw it on paper to help you visualize it better
Make same triangle
One with base 8 and another with base 15
Remember the smaller triangle can be enlarged to the larger triangle by a scale factor
The scale factor is 15/8
It is the ratio of the same side length of the 2 triangle
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Tysm
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ABC is an inscribed triangle in a circle with point O as the center. From point D on the arc BC, the angles perpendicular to the lines BC, AC, and AB are dropped at E, F, and G respectively.
a. Prove that quadrilateral DEFC is a cyclic quadrilateral.
b. Prove that E, F, and G are on a straight line.
Could someone show me how to draw this figure? (Sorry if the problem sounds a bit off, I translated it from my native language.)
@vestal bay Has your question been resolved?
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@vestal bay Has your question been resolved?
<@&286206848099549185> anyone?
for a. notice the angle DEC and DFC
for b.
3 points are on a line if their angle is 180
try using angle chase, and the fact that DEFC and DEGB are cylic
you are done if you show CEF = BEG
I don't know how to draw the figure
<@&286206848099549185> (I need help on how to draw the figure)
draw a circle
and take 4 points on it in order ABDC
make lines
AB
AC
and
BC
then make perpendicular lines from D onto AB, AC, and BC, and that is the diagram
I can't make them perpendicular
not sure why nubudy provided a sketch :c
np, odd this was open for 5h :D
are the proof layouts themselves kind of clear?
Wdym?
solving a) and b), that is
I'm a little confused on a.
@valid silo did provide useful tips :]
which property do DEC and DFC share that implies that DEFC is cyclic
The opposite angles?
yoppa
One question, why doesn't DEFC & DEGB look like a cylic in the sketch?
I didn't draw accurately lol
I used the state-of-the-art professional-approved widely in the industry used software ms paint
I used like desmos geometry to draw it accurately and it looks similar to yours
Oh we are supposed to draw extra circles?
nono
those are the circles
a cyclic quadrilateral is a quadrilateral with all of its points on a circle
so I drew the circles since you meant DFBG and DEFC don't look cyclic
regardless, for a) note that for any cyclic quadrilateral
DEC + DFC = 180° must hold
and since DEC is right-angled (perpendicular lines), DEC = 90°
and also DFC = 90°
thereby DEC + DFC = 180° is true
thereby DEFC is a cyclic quadrilateral
What property is that?
and for b) I'd use the advice shreyanjha mentioned
Opposite angles of a cyclic quadrilateral are supplementary
usually the main way to classify a cyclic quadrilateral
I don't understand the opposite part
Ohh okayy
hm you must have had some way to classify cyclic quadrilaterals in your notes
otherwise how would you know if a quadr. is cyclic
I'm a little confused on how DEC and DFC are opposite angles
DEC and DFC aren't but when the diagonals fulfill DEC + DFC = 180° then the rule holds
Could you explain this a bit more? I don't really understand the fulfill part.
ah sure misunderstood what you were confused by, it implies that the given circle must exist, wait I'll draw it
you have two right angles at the upper points
which lie on the semicircle defined by the line at the bottom
implying all four points lie on the circle described by the semicircle
it essentially directly tells you DEFC is cyclic
@vestal bay Has your question been resolved?
@strange arch could you help abit more?
@vestal bay Has your question been resolved?
@vestal bay Has your question been resolved?
it comes from this property, its in polish but i think you can understand from the picture
in this, 2alpha= 180
How would I use that to prove its a cylic?
idk, i'm just anwsering your question
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No idea how to go about solving this problem
are you familiar with how to calculate the result of a definite integral if you have the function written out
that's the fundamental theorem right?
hi guys i m new to this server
hello
you can visit #❓how-to-get-help for assistance
so here you see that
ohh thanks
you’re asked to solve the form on the left
and you’re given values for the form on the right
are you familiar with the form of an indefinite antiderivative
yes
you always add a constant +c
but that constant +c can be anything
so theres multiple forms of the antiderivative
but they only differ in the +c constant
so at x=6 you’re given the values for both F(6) and G(6)
you can calculate the difference in the +C
and from there you can find the values of all F(x) from 1 to 6
and then you can apply the fundamental theorem
correct
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A radio tower has a broadcast that can be heard in a circular area with a radius of 40 miles.
Suppose that you are driving along a straight road beginning 45 miles north of the radio tower
and ending 50 miles east of the radio tower.
Consider the radio tower to be at the origin of the Cartesian plane, i.e. the point (0,0).
(a) What is the equation of the circle that the radio broadcast can reach?
$x^2 + y^2 = 1600$
(b) What is the equation of the line the car is driving along?
$y=-\frac{9}{10}+45$
(c) What are the two points where the line intersects the circle?
$x^2+(-\frac{9}{10}+45)^2=1600$
what do I do after this?
227466
the first thing you do is patch up some discrepancies
firstly, where do these two different fractions come from
@topaz scaffold Has your question been resolved?
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it was supposed to be 9
so then you insert it into x^2 + y^2 = 1600 as the y^2
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how to integrate this 💀
it is not in root over a^2 - x^2
Just u sub 16-8x
huh 😭
u = 16 - 8x
if you insert the substitution into your integral it becomes easy to solve
yes
done
thanks a lot
damn
it wasnt that hard, i was makin it hard in mah head 😭
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how are we using logistic equations to solve this problem...?
i don't understand the 2nd and 3rd one...
so part 2 is asking when the maximum of $\frac{\mathrm{d}M}{\mathrm{d}t}$ is right?
Arnavutköy
yeah?
so the maximum of $\frac{\mathrm{d}M}{\mathrm{d}t}$ will happen when $\frac{\mathrm{d}^2M}{\mathrm{d}t^2}=0$ right?
Arnavutköy
ohh is it like local max min style stuff...? that the derivative should equal 0 and ....
yes
so do i take the derivative or?
yes
what should i do next...?
okay so you agree that one is correct right?
yeah i solved that
moreover, you would have noticed, that when $0<M<300$, that the population of meerkats is increasing right?
Arnavutköy
yes
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Maybe a dumb question but I was trying to figure out how to calculate the volume of a solid made by rotating a curve around the x axis (like Gabriel's horn) and what I thought of was first expressing the area under the 2d curve with an integral from 0 to infinite or whatever to infinity, then integrating that times the area of an arc of a circle dθ from 0 to 2pi but it doesn't work,
And I found out a common standard method is integrating the volume of a disk with radius f(x) from 0 to infinity over
It seems like the methods are pretty much equivalent but turns out I'm wrong;
Could someone explain why my method is wrong?
what exactly are you trying to do?
find the volume of gabriel's horn by rotating volume of solid?
no I meant like
I tried to derive on my own a method to calculate the volume of a solid constructed by rotating a curve
I'll try to explain myself better
Find the area under the 2d curve by integrating from 0 to infinity, then multiply that by slices of a circle
you wanna make sure that the integral of that curve from 0 to infinity converges
True
but have you heard about volume by rotation about x axis
Maybe assume the function is just defined between 2 finite bounds
So like from 1 to 5
Wdym
Like the standard method for calculating its volume?
i feel u
the formula is $\pi \int_{a}^{b} (f(x))^2 dx$
Slender
Yeah but I wanted to derive it on my own
I'm trying to figure out what's wrong with what I did because it seems like it's the same thing but in different ways
do you know how to find the volume using area of cross section
Calculate the area of a disk and integrate over the x axis or calculate the area of a slice and integrate over theta
Yeah with the thing you just sent
well it's different when you do polar coordinates
I'm not looking for practicality I just wanted to do it myself and I made something that in my head should work but doesnt
double integral comes when you try to do in terms of polar coordinates
I'm not doing polar coordinates though I mean like
Imagine for a second the volume of a slice of Gabriel's horn; not a disk, but a slice as if you were looking at it from negative x but looking to positive x and slicing it like a cake
How would you calculate that
Gabriel's horn is generated by rotating 1/x graph
Yeah
do you know the logic behind this formula
Standard way is calculating a cross sectional disk and integrating over the x axis yeah
I wanted to do it another way, calculating a slice instead of a disk
Do you see what I mean or not
Yeah I guess
Yeah so basically
You want to find the area of that slice
Since that slice is "rotated"
It forms a circle
Yeag
but the radius is variable and changing
Yup
so let the radius function be R(x)
Ok
now your area of cross section is pi * R(x)^2
Makes sense?
Each slice is of size pi * R(x)^2
Wait but that's just the standard way
Yup thats how it is
Ok so it's not what I meant
You essentially slice
So not like this?
Okay
You want to look into 2d integration
using polar coordinates
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|a| = (a•a)/|a|
How did you type that dot ?
its just because * is in front
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I think this is not the way they want me to solve it, but is there a way to do this by turning it into arctan?
If you put the 3 to the left of the integration symbol it becomes 1/(x^2 - 16)
Which is pretty close to 1/(x^2 + 1)
But im just wondering about that negative sign, cause I cant put that inside a square root
Like if it was 1/(x^2 + 16) I could easily turn it into arctan(x/sqrt(16))/sqrt(16)
Like this^^
i think this is more of a integration by partial fractions
do you know how that works
I think so, but im just wondering if this is possible
you can write this as $$\frac1{\sqrt{-16}}\arctan\left(\frac{x}{\sqrt{-16}}\right)$$
Im just curious hehe
kheerii
Yeah thats what im wondering, is this allowed?
sure
Cause the negatives are inside the square root
but it's not a very nice form to use
yes which means you'll have to deal with complex numbers
if that does not work then it is partial fractions
i would not recommend that approach lol
this problem is mostly suggesting to use partial fractions
Yeye I was just wondering if it was possible to do it this way 😝
So I guess the answer is yes but dont
alr
you can, and you can do the opposite (using partial fractions for 1 / (x^2 + 1) ) but it gets very messy
Ahh oke 😅
Well that answers my question, thank you everyone!!
❤️
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The pyramid ABCT has a triangular base where AB = 6 4. cm, AC = 5 8. cm
and ∠A = 45°. The side edge AT is 7.4 cm long and forms the angle with 60° with
the ground surface.
a) Find the area of the base.
My first approach was to use the area formula
1/2 * h * b * sin(v)
But that resulted into 1/2 * 5.8 * 6.4 * sin(45) = 13.12cm^2
Why cant I use the area formula here?
anyone who wrote amc8 today?
@lone stirrup Has your question been resolved?
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@lone stirrup Has your question been resolved?
height would be different
it is the perpendicular distance from the point above
oh you did that
@lone stirrup Has your question been resolved?
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Hi, I am struggling to understand this unit as a whole but especially how to decide whether a value will be less than and equal to, less than, etc than x/y! For example, why is x greater than/equal to -3 in this ss? I sorta forgot to restudy this unit before my final tomorrow and am freaking out a bit hahaha. Thank you!
look at the graph
Observe the function, notice how the function starts at the left then goes right, meaning x values are getting larger, larger than -3
Wait this makes sense thank you!! Let me try it out
I think im still lost. i wrote {x|-2>- x >-4
Correct
Do the y axis too
sorry the picture i sent is the teacher copy hahaha
omg the points decide that??
Yes
i thought they just decided between the brackets when writing coords
i see
'thank you
That's also another way to write it too
you can also just think of it as a lower and upper limit
especially for the y-values
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Translation for Ex 9
Idk what to do here, idk whhat to do even in "1-"
start by inserting z
@gray axle
from here try to simplify as much as possible
crunch everything into the ground
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!status
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
Show work
tbh i was just putting 1 at each side for the hexagon
i got like nothing done, i got so stuck
the fraction grayarea/totalarea is saught
yes
so you can work with any value for the sidelength or totalarea
starting with totalarea=1 can be fairly intuitive
but you can also use sidelength = 1
if you know the side-length is 1
what's the area of the hexagon?
I see there are some lines in your hexagon
Perhaps you can try forming those little triangles all over the hexagon
i mean i used sidelength = 1, and got 2.6
ill give it a shot
Sometimes the solution is much easier than you think
notice these triangles occur 6 times in the hexagon
so you can also perceive the hexagon's area as "6 * GreenTriangle"
but how many green triangles is the gray area?
1 and a bit right?
how much a bit
kk
wait is that it?
sure
what do we do now
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can anyone help me with this?
<@&286206848099549185>
Have you tried all options?
uhh I can't I only have 1 attempt
No, as in go through each option without submitting, for example, option 2
Option 2 says a rotation of the triangle by 90 degrees
But has the triangle being rotated?
ohhh
you mean like process of elimination
also sorry for late response
oh
I got the first option
as my answer
@formal ingot
Have you tried all the other options
So preimage is a reflection, right?
oh yeee
your right
so it has to be the last one right?
It would be I think
but abc is like
the original
the ones that say A'B'C' were translated 8 units right and 3 units down
I don't know if I am late, however the answer is d) triangle ABC was translated 8 units left and 3 units up if ABC means A1B1C1
8 left and 3 up
But I think you get the point
nno like
ohhh
bet bet
thanks guys
No Problem.
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Hello
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What did you do?
This absolutely isn't anywhere near my area so no promises
But your approximation of 1.066^(1/12) of 1.0055 isn't accurate at all once you raise it to the power of 240
The error gets quite large
So that could be the problem
It also looks like you copied down the result of 2.7299/0.0055 wrong from your calculator (even though those numbers aren't correct in the first place)
Assuming your formulae are correct then that's what's probably gone wrong
my formula was wrong
but @toxic grove
general question
when finding interest, we always subtract the Future Value or Present Value from our Total payments to get Interest?
Compound interest is always based on how big the debt is at that moment
when you say Interest, do you mean how much was charged in total?
Because that's just total payments minus the initial value
I've actually solved it now so I'm not totally clueless anymore
But I'm not an expert
okay
understood
ok so what i actually mean is
listen i got the right answer
and u get the R value, multiply it by 245280 which gives you the total payments, Subtract 136000 from that and u your interest correct?
@toxic grove
By R, do you mean how much he pays each month?
Because total payments would be that multiplied by 240
R value is what were solving for
The answer to part a?
R= Regular payment each compounding period
Okay yes, how much he pays each month
He pays it for 240 months, so the total payment is R * 240
But then yes, subtract 136000 from that and you get the total interest
That's how much extra paul ended up paying
ok
great
now listen carefully
mb
@toxic grove
u still here
ok now listen carefully
Ye
for 11b
this question right here
it says calculate the future value and INTEREST
correct?
Yes
I assume you know what those mean?
yes. now listen
when solving for interest. to get the right answer i had to subtract the total payment from the FV
Yes
but in this question we just did, 15b i had to subtract PV from the total payment
Okay but in the debt example, it's pretty much the same thing but in reverse
You shouldn't think of interest as a formula like that
In the debt example, interest was how much extra he had to pay on top of the 136000
Because the bank kept charging interest
It is mathematically quite similar, but present value and future value are swapped
alright so when its FV were subtracting the total payments FROM FV but when its PV were subtracting PV FROM the total payments?
Yes
It kind of feels backwards, but that's because in the debt example it was effectively you paying the interest, whereas in the annuity, the bank is paying the interest
It'll be much less confusing if you think of "interest" as an english term rather than a formula to be memorised
i kind of understand because whenver its FV, The total payments is less than the FV
but when its PV the Total payments is MORE than PV
true?
Other things are flipped as well, because in the debt example, the future value is 0, but for the annuity example, the present value is 0
Yes
understood
fully understood
im about to do this question now, last one on my exam review. tryna solve it too and we see if we got the same shit?
That's because in the debt example the bank were charging you interest (so it takes away from your payments), but in the annuity example they're paying you interest on top of your payments
got it
Sure but again no promises, I'm no economist
its descrete functions 😂
yo
@toxic grove it dont say how much money adams putting in the account per month
only ken
wtf
That's what you have to calculate
Ken puts in $100 per month and ends up with some amount of money by age 55
Adam puts in $x per month and ends up with the same amount
Solve for x
Yes
If ken puts $100 into the account each month, then he would have at least that amount by month 6
Even without interest
oh shit ur right
He pays into the account for 35 years, it's gotta be a lot more than 500 dollars
whered i go wrong
i mean
i multiplied 35 by 12
and devided 0.054 by 12
does 556x420 sound right
Where did 556 come from?
That's a bit more than what I got
Okay you're close
what did i do wrong
i forgot to subtract the 1 in the denominator
right
oh yeah
cus the its 1+i
so i is without the 1
Exactly
Yep approximately
thats my FV
Yes
ok so now we plug it in for FV into adams wuqation and solve for R
am i right
or am i right
Sounds right
finally bro
yo
@toxic grove
here we go bro
istg i have to be right
is R = 227.727
It might be
Show me your working?
I got 281 but I used a lot more precision than you did
It does feel quite far off so I don't think it's right
yeah
true
ok well
here
im right
i just typed it in the calculator
this equation equals R447.39
Alright a few problems
wats up
Firstly, how many months in 18 years?
dont even tell me
dont even tell me i reaed the calculator wrong
no fucking shot
its always somthing bro
its always somthing i swear
Hahaha it happens to all of us dw
ok dats all tho right
ok new answer; 282.34
1 problem bo
oh wait actually
i got it right on the exact decimal
282.34-100=182.34
so he had to pay 182 more dollars than his bro
and would u look at that
got it correct right down to the decimal
Yep wd
ai bro
i wana sleep but i cant
cus yo
@toxic grove my boy
he got a hold of the exam and i was looking at it
1 question i dont get that much
some quadratics shit
pretty easy
i just forget what to do
What, the actual one you're practising for?
nah nah just a old one
Okay
So what are you thinking?
Yes
ok understood
If ax^2 + bx + c = 0, then the quadratic formula will give you the possible values for x
Yes
and if u fill those in
So there are two possible solutions
those are your zerios
Yes
If you're trying to solve for the maximum height of the balloon then yeah that's one way of doing it
got it
Part (a) asks for how long it spends in the air though
and those 2 numbers that i found the axis of syetry of, 1 is probably gonna be negative and ones probably gonna be positive right?
It should be yes
i use the positive one and thats my x axis
Wdym
Yeah the positive one is the only "real" solution, the negative one is there just for mathematical reasons
How much time passed between him throwing the balloon, and the balloon hitting the ground
Yes
The balloon isn't gonna accellerate into the air so that makes sense
h(t) tells you the height of the balloon at time t right?
If h(t) > 0 then the balloon is in the air
holdup
h(0)= and solve
am i right
No
fuck
h(0) is just the height of the roof
h(t) = 0
solve for t
That's what you want to do
im saying make t=0
oh
solve for t?
dont u do that by making the equation = 0
or can u use quadratic formula
Here's what's actually happening
The red circles are where h(t) = 0
But the solution in the past doesn't really exist, because the ball was thrown to the right
Yes, you make h(t) = 0
But not t = 0
You want to find the value of t
holdup holdup holdup
so
quadratic formula gives me the zeros, but technically so does making h(t)=0
wat do i do
whic one
In theory h(t) has negative values as well but you can see they don't really mean anything
which ones faster
Then use the quadratic formula to solve for t
snm
If you know of some other way then you're welcome to use that instead
Omg my name has color now
ima use quadratic
just to be clear h(t)=0 will give me 2 brackets, i need to add a number into the brackets to make them = 0 and those numbers are my 0s right
Yes
but quadratic formula will straight up give my zeroes
If you find that h(t) = (x - 5) (x + 3) for example, then the 0s are 5 and 3
Yes sorry that's what I meant
So either you can factorise it and then work out the 0s, or you can use the formula to get the 0s (and then factorise it if you wanted)
Yes
Bottom line is it doesn't matter
Do whatever
say nm
im doing quadratic
brb gang
wait
before i go for a sec
i got a a quick question befores olving this
first: for discrimanent formula: if the x>1 = theres going to be 2 zeroes, if 0<x<1 theres going to be 1 zero, and if 0>x theres no zeroes
correct?
No
if x > 0 there are 2 zeroes, if x = 0 there is 1 zero, and if x < 0 then there are no zeroes
Yes
It makes perfect sense if you look at the quadratic formula
You can't sqrt a netagive number
And if it's 0 then +-sqrt(that) are both going to be the same
So there are still technically two zeroes, just they have the same valune
Exactly
Well
Adding nothing to one of them, and subtracting nothing from the ohter
basically the answers are going to stay the same and theya re the same
Yeah
You don't need discriminant for this question though
Go on
is itbecause the square root of -4 can be negative or positive so i ned to make it 3y-2 3y+2
positive 4, not negative
Negative 4 doesn't have a square root
But yes
2 and -2 are the two solutions to y^2 = 4
ok
and
theres this other one
i forget what its called
its where theres an a b and c value
and u square root a and c
and use the sign of b
dyk what im talking ab
No
ok for example
9y^2+12y+4
u squareroot 9y^2 and 4
and then u make it (3y+2)^2
u get what im saying
Oh are you talking about completing the square?
Well then idk what you're talking about
Not saying you're wrong
Yeah
then take b value divide it by 2, square it then add it and subtract it then take the factored number multiply it by the - one and bring it out of the bracket
Something like that yes
It's just another way of solving quadratics, you don't need to do it if you don't want to
I'd probably divide the whole thing through by 9, then complete the square
oh?
but what was that thing that the middle number (b) /2 squared or smth has to equal the c value or smth
to use the rule
That's what I always used to do when I was at school
Yeah I still don't know what you're talkinga bout
If b^2 = 4ac then the discriminant is 0 and there is only one root?
That's all I can think of
No
Oh so just (ax - b)^2 for some a?
That's literally this
I've not heard it called that before but yeah it's the same thing
ok so for the middle number
middle number has to equal to the square roots of a and c times 2
if $b = 2\cdot \sqrt a \cdot \sqrt c$ then $b^2=4ac$
depression
got it bro
love u
ima solve htat question now
the quadratic shit fam
yo
@toxic grove
im at a point where the 2 zeroes are -27-26/-9.8 and -27+26/9.8
do i solve the devision first
even tho the 2 numbers are in the numerator
Do whatever the formula tells you to do
Work out the top
Then the bottom
Then divide the top by the bototom
What is?
in the bracket
2nd equation i the ss u sent me
729+47.04
is what it should be
no?
Yeah thats right
bet
yea
nah i fucked up again
ok
i got -0.087 and 5.56
as my zeroes
ths shit actually makes no sense to me
how are my zeroes so discombobulated
Yeah that looks right
ok bet
Why wouldn't they be?
What do you think?
i think we plug 5.56 into the equation
Try it
No
Plugging in your answer to part a should give you 0
That's what you worked out
In part a
why the fuck didnt it give me zero then
What did it give you? 125?
yes
Then you typed it in wrong
If you got about 1 then it's because 5.56 isn't very accurate
But 125 means you typed it in wrong
You didn't square 5.56
i gnored the square
yup
nice
i always do smth bro
aint gon have an answer sheet on my exam
gon make so many silly mistakes
i got 1.04
Yeah
You typed it in right
But 5.56 isn't very accurate
The actual answer is 5.5977
But you probably calculated it correctly
would the answer be more accuriate if i just plugged 0 in cus that means the height when the ball was at 0m
And truncated the numbers on your page is my best guess, I wouldn't consider it a mistkae
Yes
That's the answer
wait so plugging 0 in and 5.56 in is the same thing?