Question

The curved surface area of a right circular cone is 660 cm2 and its slant height is 30 cm its radius is

Answer 1

The question looks incomplete:

We are supposed to find it's capacity.

Curved surface area of right circular cone = πrl

⇒ 600 = (22*r*30)/7

⇒ r = (600*7)/(22*30)

⇒ r = 4200/660

⇒ r = 6.36 cm

We know that,

Slant height (l)² = radius² + height²

l² = r² + h²

⇒ 30² = (6.36)² +² h² 

⇒ 900 = 40.45 + h²

⇒ h² = 900 - 40.45

⇒ h² = 859.55

⇒ h = √859.55

⇒ h = 29.31 cm

Volume of the cone = 1/3*πr²h

⇒ 1/3*22/7*6.36*6.36*29.31

⇒ 26082.71/21

⇒ 1242.03 cm²

Answer 2

**IN THIS QUESTION WE HAVE TO FIND THE VOLUME OF THE CONE.

SOLUTION :  

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

Volume of the cone (V) = 1/3× πr²h

V = 1/3× 22/7× 7 × 7 × 29.17

V = 22 × 29.17× 7 /3   = 4492.18/3  

Volume of the cone = 1497.39 cm²

Hence, the Volume of the cone = 1497.39 cm²

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