Question 1156080
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A = 2πr2 + 2πhr, solve for r.
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{{{A=2pi*r^2+2pi*hr}}}

{{{2pi*r^2+2pi*hr-A=0}}}

{{{r=(-2pi*h+- sqrt(4h^2*pi^2+8pi*A))/(4pi)}}}

{{{r=(-2h*pi+- 2*sqrt(pi*h^2+2A*pi))/(4pi)}}}

{{{highlight(r=(-h*pi+- sqrt(pi*h^2+2A*pi))/(2pi))}}}
(Look for any mistakes.)