Question

The radius of a circle whose arc of length 15 pi cm makes an angle of 3 pi/4 radian at the centre is?

Answer 1

the radius will be 20cm

angle in radian = length of arc / radius

radius = 15π/3π x 4

Radius = 20

Answer 2

Given that,

Arc of length = 15 π cm

Angle $\theta=\dfrac{3\pi}{4}$

We need to calculate the radius of a circle

Using formula of length

$l = r\times\theta$

Where, l = length or arc

r = radius of a circle

$\theta$ = angle

Put the value into the formula

$15\pi=r\times\dfrac{3\pi}{4}$

$r=\dfrac{15\pi\times4}{3\pi}$

$r=20\ cm$

Hence, The radius of a circle is 20 cm.