Alejandro R. answered • 05/24/18

Patient, supportive Tutor for High School/College Math & Science

For a cylinder:

S.A. = 2πr

^{2}+2πrh in this formula, r is the radius and h is the height. S.A. = (area of circles) + (area of tube part)

To solve question 1, you actually need to know what the radius is. Otherwise you have one equation with two unknowns.

The setup for question 2 is the same formula, except you'd plug in x for the height instead of h. Since the diameter is twice the radius, r is also equal to x. Just apply the formula above. You can cancel π out and things simplify to 400 = 4x

^{2}.Hope this helps. If you need more help, let me know.

All G.

05/25/18