Help ive been stuck for hours | Mathematics | Page 1

wide gate Oct 8, 2024, 4:50 PM

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I dont know how to solve this at all Ive tried everything please help

upper sundialBOT Oct 8, 2024, 4:50 PM

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wide gate Oct 8, 2024, 4:50 PM

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midnight parcel Oct 8, 2024, 5:01 PM

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I have a weird way that i think would work lemme show u

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it doesn’t work

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i’ll keep trying

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ok essentially i looked at it as a cross section being rotated 360

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we can find the radius and the do cosine rule to find the angle ( as we know this:

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then we use that angle to find the arc length

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we then times that by 2pi as it’s a 360 degree rotation

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then we can find this

wide gate Oct 8, 2024, 5:17 PM

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is that for surface area of the caps?

midnight parcel Oct 8, 2024, 5:17 PM

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the bottom length

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it would be 360 -2alpha

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over 2

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for beta

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and do cosine rule again

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then as there are two circles

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do 2* pi *( half the length)^2

midnight parcel Oct 8, 2024, 5:19 PM

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wide gate is that for surface area of the caps?

i am almost certain i am doing this a WAY overly complicated way

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but i dont see why it wouldn’t work

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btw r is just half the diameter

wide gate Oct 8, 2024, 5:20 PM

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I got 89.135 for angle so would arc length be s=rtheta?

midnight parcel Oct 8, 2024, 5:21 PM

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as that’s in degrees

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it would be 89.135/360x2pir

wide gate Oct 8, 2024, 5:28 PM

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so after that you do what?

2pi(5.7)(8.867)?

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or do you have to find centroid of the cap

wide gate Oct 8, 2024, 6:16 PM

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This is where I’m at

midnight parcel Oct 8, 2024, 6:31 PM

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and that gives the total surface area i’m pretty sure

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so times the green by 2pi

wide gate Oct 8, 2024, 6:32 PM

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what is the green the length of it?

midnight parcel Oct 8, 2024, 7:01 PM

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u need to find the arc length and then add 2 of the length on the side

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which u can work out by doing some pythag

wide gate Oct 8, 2024, 7:20 PM

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I did its in the pic 8.86748

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I added entire length of green and multiply it by 2pi and it was wrong

midnight parcel Oct 8, 2024, 8:34 PM

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oh

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idk then

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probs a mistake at the start or smt idk

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idk how else to do it

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there is defo a shortcut tho

wide gate Oct 8, 2024, 8:36 PM

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hmm ok ill prob ask my prof but thanks for ur help

midnight parcel Oct 8, 2024, 8:38 PM

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How did u solve for the bottom length

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wide gate Oct 8, 2024, 8:45 PM

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Found the angle of 90.86 which forms upper and lower archs then / 2 to form right triangle 4.06 = 4tan(45.43)

midnight parcel Oct 8, 2024, 8:46 PM

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ok nice

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not sure what uve done wrong

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or if there is a flaw in the method

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hold on

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how about u try

#Help ive been stuck for hours