# Maths

Make r the subject of formula t=2πr(r+h)

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1. so you will be re-arranging to get r all by itself...
it is a wee bit tricky due to the r inside and outside of the bracket.
Do you usually treat it like a quadratic and factor it?
Because that would be a lovely solution : )

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2. t=2πr(r+h)
t = 2πr^2 + 2πhr
2πr^2 + 2πhr - t = 0
this is a quadratic in r, where a = 2π , b = 2πh and c = -t

r = (-2πh ± √(4π^2h^2 - 4(2π)(-t) )/(4π)

see if you can simplify that

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3. explain in detail

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4. I don't understand

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5. I don understand

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6. I don’t understand

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