a. We assume you want the dot product. That is the sum of the products of the corresponding components.
... V1•V2 = (-6)(-3) + (4)(6) = 18 + 24 = 42
b. V1•V2 = |V1|·|V2|·cos(α)
... α = arccos(V1•V2/(|V1|·|V2|)
... α = arccos(42/√(((-6)²+4²)((-3)²+6²)))
... α = arccos(42/√2340)
... α ≈ 29.74°
c. The scalar projection of V1 onto V2 is the dot product of V1 with the unit vector in the V2 direction.
... V1•V2/|V2| = 42/√45 = 42/(3√5) = (14/5)√5
d. The projection of V1 onto V2 is the result of part c multiplied by the unit vector in the direction of V2.
... projection of V1 onto V2 = (14/5)√5·(-3, 6)/(3√5) = (14/5)(-1, 2) = (-14/5, 28/5)
