# Find the slant height of a frustum cone whose top radius is 12 m and bottom radius is 10 m. The height of the cone is 13 m.

(A) 13.15 m

(B) 12.15 m

(C) 10.15 m

(D) 14.25 m

Solution:

Height of the cone, h = 13 m

Bottom radius, r1 = 10 m

Top radius, r2 = 12 m

Slant height, l = √(h2 + (r2-r1)2)

= √(132 + (12-10)2)

= √(169 + 4)

= √173 m

= 13.15 m

Hence option A is the answer.