Question

find the volume of the frustum of base radii 7cm and 3.5cm and height 2cm

Answer 1

Volume of the frustum = 1/3 πh( R² + r² + Rr)

Here
         R = 7 cm         
         r = 3.5 = 7/2 cm
         h = 2 cm

Volume = 1/3 ×22/7×2( 7²+ (7/2)²+7×7/2)
             = 44/21( 49 + 49/4+ 49/2)
             = 44/21 × 49( 1+ 1/4+ 1/2) = 44 / 3 × 7 ( 1 + 6/8)
             = (44/3) × 7 × (14 /8) = 4312 / 24
             = 179.67 cm³