Q. 59

# The area of the b

Answer :

Given: Area of the base of a right circular cone is 154 cm2.

Height of the cone is 14 cm.

Curved surface area of a cone is : πrl (here r and l are radius and slant height respectively)

Area of the base is given by: πr2

π × r2 = 154

r2 = = 49

r = 49 = 7cm

radius of the base of the cone is 7cm

Now,

l = √(r2 + h2)

πrl = πr√(r2 + h2)

Let S be the CSA of the cone.

S = πr√(r2 + h2)

S = π × (7) × √((7)2 + (14)2)

S = π × (7) × √(49 + 196) = π × (7) × √(245)

S = π × (7) × 7√5 = × 7 × 7√5 = 154√5

S = 154√5 cm2

That is CSA of the cone is 154√5 cm2

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