Dot Product Concept

For dot product we know that a•b=|a|•|b|cos theta and also when any two vectors are orthogonal/perpendicular to one another they form an angle of 90° By inputting the value of 90° into the formula we have that;a•b=|a|•|b|cos 90° cos 90°=0 So,a•b=|a|•|b|0 =0

In terms of plane geometry, orthogonal vectors are mutually perpendicular. Since dot product of two vectors involve the cosine of the angle between them, and since $\cos 90\degree=0$ , dot product of two orthogonal vectors is zero