[tex]\qquad\qquad\huge\underline{{\sf Answer}}[/tex]
According to first law of reflection, we know that :
Angle made by the incident ray and normal [ i.e angle of incidence ] is always equal to Angle made by the reflected ray and normal [ i.e Angle of reflection ]
Therefore, we can say that the missing angle (angle of reflection) has the same value as the angle of incidence which is equal to 45°
Please read the statement through to understand the procedure ~
