
If AB is the position of the face of man then A′B′ is the position of the image of a face. As the image is formed at 25cm from the object.∴ From concave mirror image is 15cm behind the mirror. So, u=−10cm,v=+15cm
⇒f1=u1+v1⇒f1=−101+151=30−3+2
⇒f=−30cm. So, the radius of curvature,=60cm