Mensurationhard · Past Paper
What is the total surface area of a frustum of a cone with radii 4 cm and 2 cm and height 4 cm?
A48π sq. cm
B(24√5 + 20)π sq. cm
C52π sq. cm
D60π sq. cm
✓ Correct Answer: B — (24√5 + 20)π sq. cm
l = √(h² + (R-r)²) = √(16 + 4) = 2√5. TSA = π(R+r)l + πR² + πr² = π(6)(2√5) + 16π + 4π = 12√5π + 20π.
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