Question 868259
to isolate or solve for r in the equation SA=2pier^2=2pierh

*pie is the pie sign
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Too many equal signs.
pi is the Greek letter pi, not the dessert, pie
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For a cylinder:
{{{SA=2pi*r^2 + 2pi*rh}}}
{{{2pi*r^2 + 2pi*rh - SA = 0}}}
r = {{{(-2pi*h +- sqrt(4pi^2h^2 + SA*8pi))/(4pi)}}}