Explanation:
Divide the solid into 2 cones.
SA of a cone
= πrl
l of cone 1
l² = r² + h²
l² = 9² + 12²
l² = 81 + 144
l² = 225
l = √225
l = 15cm
SA of cone 1
= πrl
= π × 9 × 15
= π × 135
= 135π
l of cone 2
l² = r² + h²
l² = 9² + 40²
l² = 81 + 1600
l² = 16081
l² = 126cm
SA of cone 2
= πrl
= π × 9 × 126
= π × 1134
= 1134π
SA of solid
= 135π + 1134π
= 1269π