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