The radius of the circle whose arc of length `15\ pi` cm makes an angle of `(3pi)/4` radians at the centre is

Options

A. 5 cm
B. 10 cm
C. 15 cm
D. 20 cm

Answer

D

Explanation

Here, агc length `l=15 pi cm`


Angle `theta=frac{3 pi}{4}`


We know, angle subtended by the arc is given by,


`theta=frac{text { length of arc }}{text { radius }}`


`therefore` radius `=frac{1}{theta}`



`=frac{15 pi}{3 pi} times 4`


`=20 cm`