Scalar or Dot Product

The scalar product of two vectors is a scalar quantity. Therefore, the product is called scalar product.

Sign of Dot Product

The dot product may be positive or negative or zero.

1. If the angle between the two vectors is acute (0° < θ < 90°) then cos θ is positive. In this case, dot product is positive.

2. If the angle between the two vectors is obtuse (90° < θ < 180°) then cos θ is negative. In this case, dot product is negative.

3. If the angle between the two vectors is 90° (θ = 90°) then cos θ = 0. In this case, dot product is zero.