Question

height of a cone is 30cm, its slant height is 32 cm, then the radius is- ?

Answer 1

Given:

Height of a cone is 30cm, its slant height is 34 cm.

To find:

The radius of the cone.

Solution:

Using the Pythagoras theorem, the relation between Height, radius and slant height is

$r^2+h^2=l^2$

$r^2=l^2-h^2$

Where, r is radius, h is height and l is the slant height.

Putting the given values, we get

$r^2=(34)^2-(30)^2$

$r^2=1156-900$

$r^2=256$

Taking square root on both sides.

$r=\pm\sqrt{256}$

$r=\pm 16$

Radius cannot be negative. So, r=16 cm.

Therefore, the correct option is b.