What is the angle of incidence of a ray if the reflected ray is at an angle of 90° to the incident ray?

Question

What is the angle of incidence of a ray if the reflected ray is at an angle of 90&#xB0; to the incident ray?

Philoid · Accepted Answer

From the laws of reflection,

The angle of incidence (∠i) = angle of reflection (∠r) Here as given ∠i + ∠r = 90°

∴ ∠i + ∠i = 90°
2∠i = 90
∠i = 90/2

∠i= 45 °

Hence angle of incidence of a ray = 45°