Question

Find a ⋅ b. a = 10i + 9j, b = 4i + 3j

Answer 1

a ⋅ b = 67

Explanation:

We have been given that

a = 10i+9j

b = 4i +3j

The dot product of a ⋅ b is given as

`a\cdot b=(10i+9j)( 4i +3j)\\\\=10i\cdot4i+30ij+9i\cdot3j+36ij`

Now, we know that

i⋅ i = 1

j ⋅ j=1

i⋅ j=0

Hence, we have

`10i\cdot4i+9i\cdot3j=40+27\\\\=67`

Therefore, we have

a ⋅ b = 67