Question

The radii of circular ends of frustum of a cone are 20 cm and 12 cm and its height is 6 cm. Find the Slant height of frustum.

Answer 1

Given: Radii r₁ = 20 cm, r₂ = 12 cm; height h = 6 cm.

Use `l = sqrt(h^2 + (r_1 - r_2)^2)` for slant height of a frustum.

Step-wise calculation:

1. r₁ – r₂ = 20 – 12

= 8 cm

2. (r₁ – r₂)² = 8²

= 64

3. h² = 6²

= 36

4. h² + (r₁ – r₂)²

= 36 + 64

= 100

5. `l = sqrt(100)`

= 10 cm

The slant height of the frustum is 10 cm.