If someone wants to see around 90 * corner, at what angel would they have to place a mirror

if someone wants to see around 90 * corner, at what angel would they have to place a mirror

Explanation:

There is no refraction at 90 degree angleThis is because the angle of incidence can become large enough so that the angle of refraction, being even larger, can reach 90 degrees. This eliminates the possibility that the ray will enter the refracted medium. These conditions demonstrate what is known as a critical angle

Angle of incidence is the angle an incident light ray makes with a normal drawn to the surface ... Thus, an angle of reflection of 90 degrees is caused by an incident ray that has an angle of incidence of 90 degrees. An angle of reflection of 90 degrees means that the reflected ray travels along the surface.