Find a.b if a = 8i + 6j, b = 4i + 5j

Solution:

Given, a = 8i + 6j, b = 4i + 5j

We have to find a.b

If the two vectors are expressed in terms of unit vectors, i, j, k, along the x, y, z axes, then the scalar product is given by

a.b = a₁b₁ + a₂b₂ + a₃b₃

Here, a₁ = 8, a₂ = 6, b₁ = 4 and b₂ = 5

a.b = (8i + 6j).(4i + 5j)

= 8(4) + 6(5)

= 32 + 30

= 62

Therefore, a.b = 62

Find a.b if a = 8i + 6j, b = 4i + 5j

Summary:

If a = 8i + 6j, b = 4i + 5j, then a.b is 62.