The pin method is used to prove the law of reflection in optics. The angle of incidence is equal to the angle of reflection. So here the angle of incidence is 30degree. Hence the angle of reflection is also 30 degree. But the angle between the incident ray and the reflected ray is 2*30=60 degrees. because
Below are the characteristic of mirror:
1)Image is virtual.
2)right-left inverted image
3)snell's law holds good
4)reflected light ray is 180 degree phase shifted