A right circular cone having the total surface area of 314 cm² and radius of 7 cm. What is the slant height of the cone?
Show answer & explanation
Correct answer: B
Explanation
Given:
Total surface area = 314 cm²
Radius = 7 cm
By formula:
Total surface area = πr(r + l)
314 = π × 7 × (7 + l)
Substituting π = 22/7
314 = (22/7) × 7 × (7 + l)
314 = 22(7 + l)
314 = 154 + 22l
314 − 154 = 22l
160 = 22l
l = 160 / 22
l = 80 / 11 = 7.2 cm