The angle of incidence in reflection is equivalent to the angle of reflection. This principle is based on the law of reflection, which states that the angle at which a wave, such as light, hits a surface equals the angle at which it bounces off. Therefore, when light strikes a surface, if the angle of incidence is measured from the normal (a perpendicular line to the surface), the reflected ray will emerge at the same angle in relation to the normal. This fundamental principle is crucial in optics and helps explain various phenomena, such as mirrors and reflections in water.