The radius of a solid right circular cone is 65 cm, and its height is 72 cm. The total surface area (in cm²) of the cone is (use π = 22/7):
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e .
Total surface area (TSA) = πr(l + r)
where r = radius, l = slant height, h = height.
l = √(r² + h²) = √(65² + 72²)
⇒ √(4225 + 5184) = √9409 = 97 cm
TSA = (22/7) × 65 × (97 + 65) = (22/7) × 65 × 162 = (231660/7) = cm²