A drinking glass is in the shape of frustum of a cone of height 21 cm with 6 cm and 4 cm as the diameters of its two circular ends. Find the capacity of the glass.
Given: Height of glass = h = 21 cm
Diameter of lower circular end of glass = 4 cm
Diameter of upper circular end of glass = 6 cm
∴ Radius of lower circular end = r = 4/2 = 2 cm
∴ Radius of upper circular end = R = 6/2 = 3 cm
Capacity of glass = volume of frustum
= 22 × (9 + 4 + 6)
= 22 × 19
= 418 cm3
∴ Capacity of glass = 418 cm3
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