the right circular cylinder has radius r and height h. not including its bases, the surface area of the cylinder is 2(pi)rh. if this surface area not including the bases is 70(pi), what is the volume of the cylinder in terms of r?

Question

anonymous · Answer

Do you know the equation for the volume of a cylinder?

anonymous · Answer

$$V = \pi r^2 h$$
$$A_s = 2 \pi r h$$
$$r = \frac {A_s}{2 \pi h}$$

plug n chug

anonymous · Answer

errr, I guess it wants you to sub in h, not r.  My bad.

$$h = \frac{A_s}{2 \pi r}$$

anonymous · Answer

yeah it didn't really give me anything just that it a PSAT question

anonymous · Answer

Can you solve it from here?

anonymous · Answer

yeah I think so

anonymous · Answer

^^  Happy PSAT studying

anonymous · Answer

If you want to remember the volume, an easy way to see that it's just a bunch of circular areas stacked on top of each other.

$$A_{circle} = \pi r^2$$

Volume of right cylinder height h

$$V = h (\pi r^2)$$