Question

The radius and slant height of a cone are in the ratio of 4:7.If its curved surface area is $792c{m}^2$,find its radius.(Use $\pi =\frac{22}{7})$

Answer 1

Curved surface area of a cone=792 $c{m}^2$

Ratio in radius and slant height=4:7

Let radius =4x

Then Slant height=7x

$\therefore Curvedsurfacearea,\pi rl=792\Rightarrow \frac{22}{7}\times 4x\times 7x=792\Rightarrow 88x^2=792\Rightarrow x^2=\frac{792}{88}=9\Rightarrow x=\sqrt{9}=3\therefore Radius=4x=4\times 3=12cm$