Expert: Bobby Soltani - 10/9/2005

Question
if the base area of right circular cylinder is 7 sq cms & its volume is 77 c.c,find its height & total surface area.

note; if you have any informable website about the following above topic please tell me.

Answer
Hi Ahmed,

Let's first write out the applicable formulas.

V = (pi)*(r^2)*(h)

B = (pi)*(r^2)
where B is base area.  Therefore, we can substitute for pi*r^2.

V = B*h
We know that B is 7 and v = 77, so we can solve for h

77 = 7*h
divide both sides by 7
h = 11

The total surface area is the area of the cylinder part plus the area of each of the ends.

The area of the cylinder part = 2*pi*r*h
The area of one base = pi*r^2

The total surface area is
2*pi*r*h + 2*pi*r^2

The two variables in this equation are r, and h.  We are given h, so we need to find r.

B = pi*r^2
7 = pi*r^2
r^2 = (7/pi)
r = SQRT(7/pi)
r = 1.493

Plug r = 1.493 and h = 11 into the formula for total surface area.

Let me know if you have any questions.

Bobby