Question

An arc of length 20𝜋 cm subtends an angle of 144° at centre of circle. Find the radius of the circle.

Answer 1

Length of arc = 20𝜋cm

Let radius = ‘r’ cm

O = angle subtended at centre = 144°

Length of arc =`theta/360^@`× 2𝜋𝑟

=`144/360× 2pir =(4pi)/5r`

=`(4pi)/5r = 20pi`

`r =(20pi×5)/(4pi)`= 25 cms