Question

If the curved surface area of a right circular cone is 660 cm² and base radius is 10 cm then find the slant height of the cone.​

Answer 1

Answer:

Given : C.S.A of a right circular cone = 660 cm²

slant height of cone,  (l)= 30 cm

Curved surface area of right circular cone (C.S.A) = πrl

660 = 22/7 × r × 30

r = (660 × 7)/(22 × 30)

r = 22 × 7 /22

r = 7 cm

Slant height (l)² = r² + h²

(30)² = (7)² + h²  

900 = 49 + h²  

h² = 900 - 49

h² = 851

h = √851

h = 29.17 cm

(V) = 1/3× πr²h

V = 1/3× 22/7× 7 × 7 × 29.17

V = 22 × 29.17× 7 /3   = 4492.18/3  

= 1497.39 cm²