Question

Two cones are similar. The surface area of the larger cone is 65π square inches. The surface area of the smaller cone is 41.6π square inches. The radius of the smaller cone is 6.4 inches. What is the radius of the larger cone? 8 inches 10 inches 11.52 inches 14.4 inches

Answer 1

Answer:

8

Step-by-step explanation:

Ed2020

Answer 2

Answer:

8 inches

Step-by-step explanation:

The surface area of a cone (without the base) is given by:

Surface area = pi*r*s

Where r is the base radius and s is the slant height.

The smaller cone has a surface area of 41.6pi in2 and a radius of 6.4 inches, so the slant height is:

41.6pi = pi*r*s

41.6 = 6.4s

s = 6.5 in

If the cones are similar, the radius and the slant height increase in the same proportion, so we have that:

r'/s' = r/s = 6.4/6.5

s' = r'*6.5/6.4

So for the larger cone, we have:

65pi = pi*r'*s'

65 = r'*r'*6.5/6.4

r'^2 = 64

r' = 8 inches