had a maths exam, was wondering how you guys would approach this question | Mathematics | Page 1

orchid saddleBOT Nov 28, 2023, 5:15 PM

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autumn perch Nov 28, 2023, 5:15 PM

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eager kestrel Nov 28, 2023, 5:17 PM

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is anything else known here?

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right now there is not enough info

autumn perch Nov 28, 2023, 5:18 PM

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nah there is surely

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its a heptagon

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im just wondering how others would work this out

gleaming pendant Nov 28, 2023, 5:25 PM

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there's no way to do this bruh

autumn perch Nov 28, 2023, 5:25 PM

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how

gleaming pendant Nov 28, 2023, 5:25 PM

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you have to have more information

autumn perch Nov 28, 2023, 5:25 PM

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nah

gleaming pendant Nov 28, 2023, 5:25 PM

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if you have side length

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it's defo possible

autumn perch Nov 28, 2023, 5:25 PM

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its enough

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yea work it out

gleaming pendant Nov 28, 2023, 5:25 PM

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did you get it?

autumn perch Nov 28, 2023, 5:25 PM

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i think so

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idk i only did it today but i wanna know how others would do this question

gleaming pendant Nov 28, 2023, 5:25 PM

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how'd you go ahead with it

autumn perch Nov 28, 2023, 5:25 PM

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so i did right

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u can work out interior angles

gleaming pendant Nov 28, 2023, 5:26 PM

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first i tried to drop a perpindecular from b

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name it o

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then im stuck

autumn perch Nov 28, 2023, 5:26 PM

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(n-2) x 180

gleaming pendant Nov 28, 2023, 5:26 PM

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you need to know side

autumn perch Nov 28, 2023, 5:26 PM

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so 5x180 = 900

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900/7 = 128

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each angle is like 128.78 blah blah

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then u got 30cm^2 = 0.5(a)(b)sin128

gleaming pendant Nov 28, 2023, 5:27 PM

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wait was calculator allowed?

autumn perch Nov 28, 2023, 5:27 PM

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ye

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it was calc paper

gleaming pendant Nov 28, 2023, 5:27 PM

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oh shit

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go ahead

autumn perch Nov 28, 2023, 5:27 PM

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then sin128 is like 0.78

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so 30cm^2 = 0.5x0.79xAxB

gleaming pendant Nov 28, 2023, 5:28 PM

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what's a and b here

autumn perch Nov 28, 2023, 5:28 PM

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0.5 x 0.79 = 0.38

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bcs we have angle opposite c

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so its 30cm^2 = 0.39 ab

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30/0.39 = 249

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a = b because its heptagon all angles are the same

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so 249 = a^2

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249^1/2 = 8.67 smth like that

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then u have a and b just do cosine rule and get c

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is this how u guys would answer this?

gleaming pendant Nov 28, 2023, 5:31 PM

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autumn perch then u got 30cm^2 = 0.5(a)(b)sin128

you applied trignometry to a non right triangle

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or am i wrong

autumn perch Nov 28, 2023, 5:31 PM

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area of non right angled trangle = 0.5absinc

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in this case a = b

compact thunder Nov 28, 2023, 5:32 PM

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if you know that this is a regular heptagon you can figure out the side length

gleaming pendant Nov 28, 2023, 5:32 PM

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interesting way to do it

autumn perch Nov 28, 2023, 5:32 PM

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gleaming pendant interesting way to do it

is this how you would have done it

gleaming pendant Nov 28, 2023, 5:32 PM

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i was brought up in an education system where we have never used a calculator

autumn perch Nov 28, 2023, 5:32 PM

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compact thunder if you know that this is a regular heptagon you can figure out the side length

yuh

autumn perch Nov 28, 2023, 5:32 PM

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gleaming pendant i was brought up in an education system where we have never used a calculator

💀

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what education system is this

gleaming pendant Nov 28, 2023, 5:33 PM

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cbse

autumn perch Nov 28, 2023, 5:33 PM

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tf is that

gleaming pendant Nov 28, 2023, 5:33 PM

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central board of secondary education

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the only time i have used a calculator

autumn perch Nov 28, 2023, 5:33 PM

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what country

gleaming pendant Nov 28, 2023, 5:33 PM

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is when i took the sat

autumn perch Nov 28, 2023, 5:33 PM

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oh usa

gleaming pendant Nov 28, 2023, 5:33 PM

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autumn perch what country

i live in abu dhabi but the cirriculum is indian

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cbse is from india

compact thunder Nov 28, 2023, 5:33 PM

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i would create a right triangle with side a and since this is a regular heptagon we can figure out the angles

autumn perch Nov 28, 2023, 5:34 PM

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compact thunder i would create a right triangle with side a and since this is a regular heptagon...

you already have the angles

gleaming pendant Nov 28, 2023, 5:34 PM

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gleaming pendant the only time i have used a calculator

istg i was so suprised when my calculator could solve the zero's of a polynomail

compact thunder Nov 28, 2023, 5:34 PM

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autumn perch you already have the angles

bisection stuff

autumn perch Nov 28, 2023, 5:34 PM

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its a heptagon each angle is the same there are 7 sides

gleaming pendant Nov 28, 2023, 5:34 PM

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compact thunder bisection stuff

that's how i tried approaching it

autumn perch Nov 28, 2023, 5:34 PM

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oh right

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would have just re arranged a few steps

compact thunder Nov 28, 2023, 5:35 PM

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Screenshot_2023-11-28_at_12.35.15_PM.png

gleaming pendant Nov 28, 2023, 5:35 PM

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cant wait to leave this treacherous education system

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then get into a good uni

autumn perch Nov 28, 2023, 5:36 PM

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yea that would have worked also

gleaming pendant Nov 28, 2023, 5:36 PM

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they make you do 0.021/0.0061 without using calculator or log table

compact thunder Nov 28, 2023, 5:36 PM

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we figure out c/2 and this unknown side relative to a

gleaming pendant Nov 28, 2023, 5:36 PM

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compact thunder we figure out c/2 and this unknown side relative to a

if one side was given, this problem could be solved much easier

autumn perch Nov 28, 2023, 5:37 PM

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it was the last question of the paper

compact thunder Nov 28, 2023, 5:37 PM

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we just pull the ratios of what c/2 and this unknown side must be

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and then we know that the area of this triangle must be 15cm^2

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and then we get the actual side lengths and then pythagorean theorem it to get a

autumn perch Nov 28, 2023, 5:37 PM

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but

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you dont know what c or d is

gleaming pendant Nov 28, 2023, 5:38 PM

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wait how'd you get c or d

autumn perch Nov 28, 2023, 5:38 PM

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yea thats what im thinking

compact thunder Nov 28, 2023, 5:38 PM

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we dont need to know that

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yet

autumn perch Nov 28, 2023, 5:38 PM

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if you already know c you can just multiply it by 2 because thats all the question is asking fro

gleaming pendant Nov 28, 2023, 5:38 PM

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autumn perch if you already know c you can just multiply it by 2 because thats all the questi...

💀

autumn perch Nov 28, 2023, 5:38 PM

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then you how can use pythagoras to get it sad_think

compact thunder Nov 28, 2023, 5:38 PM

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oh you did not want the area of the whole heptagon lmao

gleaming pendant Nov 28, 2023, 5:38 PM

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i have a chemistry exam tmrw what am i doing here

autumn perch Nov 28, 2023, 5:38 PM

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question asks for c

compact thunder Nov 28, 2023, 5:38 PM

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ok in that case this problem is easier

gleaming pendant Nov 28, 2023, 5:39 PM

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procrastination at its finest

compact thunder Nov 28, 2023, 5:39 PM

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find the ratio of what c/2 and what this unknown side has to be

autumn perch Nov 28, 2023, 5:39 PM

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asks for yellow line

compact thunder Nov 28, 2023, 5:39 PM

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so like lets say this unknown side is like

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1/4th the length of c/2

autumn perch Nov 28, 2023, 5:39 PM

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this way to calculate it sounds long asf

compact thunder Nov 28, 2023, 5:39 PM

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then we get that (c/2)(c/4)=30

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and then boom you have

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c

autumn perch Nov 28, 2023, 5:40 PM

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yea idk how that works

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gleaming pendant Nov 28, 2023, 5:42 PM

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isntead of dividng by 7, you just divide by 14

autumn perch Nov 28, 2023, 5:42 PM

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yh

gleaming pendant Nov 28, 2023, 5:42 PM

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you'll get what cat bred was telling about

#had a maths exam, was wondering how you guys would approach this question