Question

A right circular cylinder has a surface area of 66π. If the height of the cylinder is 8, find the diameter of the base.

Answer 1

Answer:

6

Step-by-step explanation:

h = 8

Surface area = 66π

2πr(r +h) = 66π

2πr(r + 8) = 66π

$r(r + 8) =\dfrac{66\pi }{2\pi }$

r² + 8r = 33

r² + 8r - 33 = 0

r² + 11r - 3r - 33 = 0

r(r + 11) - 3(r + 11) = 0

(r +11 ) (r - 3) = 0

r - 3 = 0             {Ignore r = -11 as radius will not have negative value}

r = 3

Diameter = 3*2 = 6 units