Any geometry experts out there?

[Alex Berkovsky]

My kid has a geometry problem to solve and I am not much help. Here's what's given:

Find the radius and height of a cylinder if the height is 3 less than the radius and TSA=70π (Pi)

I got this far and that's all I remember from my last geometry class 33 yrs ago.

TSA = 2πr(r+h)

70π = 2πr(r+h)
70π = 2πrh+2πr²
70π = 2πr(r-3)+2πr²
70π = 2πr²-3r+2πr²
70π = 4πr²-3r

[Dan Hintz]

From the problem description,
TSA = 2πr(r+h) = 70π
h = r-3.

Plug in, we get:
70π = 2πr(r + (r-3))
70π / 2π = r(2r - 3)
35 = 2r^2 - 3r
2r^2 - 3r - 35 = 0

Solve via quadratic equation for r...

I think that's correct...

Two roots: 5 and -3.5. It's a real cylinder, so 5 must be it.