Question

The slant height of the frustum of a cone is 5 cm. If the difference between the radii of its two circular ends is 4 cm, write the height of the frustum.

Answer 1

Slant height of the Frustum = 5 cm

`i.e . l = 5 cm.`

`r_1 - r_2 = 4cm.`

`l = sqrt(h^2 + (r_1 - r_2)^2)`

`5 = sqrt(h^2 + (4)^2)`

Squaring both sides we get

`25 = h^2 + 4^2`

`25 = h^2 + 16`

`25 - 16 = 4^2`

`or  h^2 = 9  cm`

`4 = 3  cm`

Height of the Frustum = 3 cm