A cone of height 24cm has a C.S.A 550m2 .Find its volume (pie =22/7)
Given height of the cone, h = 24 cm
Let r cm and l cm be the radius and slant height of the cone respectively.
Curved surface area of the cone = 550 cm2 (Given)
∴ πrl = 550 cm2
Squaring on both sides, we get
r 2 (r 2 + 576) = (175)2 = 30625
∴ r 4 + 576 r 2 – 30625 = 0
⇒ r 4 + 625 r 2 – 49 r 2 – 30625 = 0
⇒ r 2(r 2 + 625) – 49 (r 2 + 625) = 0
⇒ (r 2 + 625) (r 2 – 49) = 0
⇒ r 2 – 49 = 0 ( ∵ r 2 + 625 ≠ 0)
⇒ r 2 = 49
⇒ r = 7 ( ∵ Radius cannot be negative)
Radius of the cone = 7 cm
∴ Volume of the cone
Thus, the volume of cone is 1232 cm3.