Correct Answer - Option 1 : 55 Π
Given:
Frustum of cone having base radius 7 cm, upper radius 4cm and height 4 cm
Formula Used:
CSA of frustum of cone = Π (R + r) × l
Where, l = slant height of frustum
Also, l = √[(R - r)2 + h2]
Calculation:
l = √[(R - r)2 + h2] = √[(7 - 4)2 + 42]
= √[(3)2 + 42]
= √(9 + 16)
= √(25) = 5 cm
∴ CSA of frustum of cone = Π × (7 + 4) × 5
= 55 Π
