Question

If the radius and slant height of a cone are in the ratio 7:13and its courved surface area is 286cm2 find it's radius​

Answer 1

Let the radius 'r' of cone be 7x cm

and slant height 'l' be 13x cm

CSA of cone=286 cm²

$= > \pi \times r \times l = 286 \\ = > \frac{22}{7} \times 7x \times 13x = 286 \\ = > 13 {x}^{2} = \frac{286}{22} \\ = > 13 {x}^{2} = 13 \\ = > {x }^{2} = 1 \\ = > x = 1$

Therefore, radius of cone is 7cm and slant height is 13cm.

Hope it helps you

Answer 2

Answer:

Let r/1 = 7/13x

Curved surface area CSA=286 cm2

But CSA=πrl

∴286 = 22/7 × 7x × 13x

or x2 = 286/22×13 = 1

or x = 1

∴ r=7 cm

∴ Diameter d=14 cm