Suppose vector a is 3 units long, the magnitude of vector b is 1 units and cos (θ) = -0.3, where θ is the angle between the two vectors when they are placed tail-to-tail. What does the inner product of vector a and vector b equal?

Answer 1

a.b = |a|*|b|*cosθ
= 3 * 1 * (-.3) = -.9