surface area of cylinders | Mathematics | Page 1

sinful socket Jan 22, 2023, 10:31 PM

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Is "the cylinder below" the one to the right and not below?

real tangle Jan 22, 2023, 10:33 PM

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yes@sinful socket

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you wanna do 1 and I'll do 2? or other way

tardy yarrow Jan 22, 2023, 10:34 PM

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both bro

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im hella struggling

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im so shit at maths

real tangle Jan 22, 2023, 10:39 PM

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I'll do 2 anyway
so to start off you have:
2 flat rectangles
2 half circle arcs
inside and outside arc

the rectangles are (20-12)×50 so 400cm²

the half circle arcs are 2(½πr²-½π(r-4)²) so 100π-36π=64π

inside arc is ½2πr so πr×50 for inside and outside
inside: 50×π×6=300π
outside: 50×π×10=500π

together you have (500π+300π+64π+400)cm² or (864π+400)cm² which is roughly 3114cm²

tardy yarrow Jan 22, 2023, 10:39 PM

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your amazing

real tangle Jan 22, 2023, 10:42 PM

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1 is 2πx²+2xπ×5x=972 so 2πx²+10x²π=972 so 12πx²=972
x=√(81/π)
x=9/√π

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oh it's 972π

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so x=9

tardy yarrow Jan 22, 2023, 10:43 PM

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ye

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tysm tho bro your a life saver on god

#surface area of cylinders