A frustum of a right circular cone has a diameter of base 20 cm, of top 12 cm, and height 3 cm. Find the area of its whole surface and volume.

For frustum:

Base radius, r’ = 20/2 = 10cm


Top radius, r’’ = 12/2 = 6cm


Height, h = 3cm


Volume =



= 616 cub. cm


Let l be the slant height of the cone, then




l = 5cm


Total surface area of the frustum = π (r’ + r’’) × l + π r’2 + π r’’2


= π (20 + 10) × 15.620 + π (10)2 + π (6)2


= 678.85 cm2


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