Q. 155.0( 2 Votes )

# Find the curved surface area and total surface of a cone whose height is 28 cm and diameter is 42 cm.

Given, the diameter of the cone = 42 cm
∴Radius = 42 cm ÷ 2 = 21 cm, h = 28 cm
slant height l = √(h2 - r2) = √(282 - 212) = 𢆧흉 = 7�m
Curved surface of cone = π rl
= × 21 × 7𢆧 = 462�m2
∴Total surface area of cone = π r(l + r)
= × 21 × (7𢆧 + 21)
= 462(𢆧 + 3)cm2

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