Question

Find the inner product for (7.2) (0,-2) and state whether the vectors are perpendicular.

a. -4; no

c. 4; no

b. -4; yes

d. 4; yes

Answer 1

a. -4; no

Explanation:

Suppose we have two vectors, a and b.

a = (1,2)

b = (2,3)

Their inner product is:

a.b = (1,2).(2,3) = 1*2 + 2*3 = 8

The vectors are perpendicular if their inner product is 0.

In this question:

a = (7,2)

b = (0,-2)

So

a.b = (7,2).(0,-2) = 7*0 + 2*(-2) = -4

-4 is different of 0, so they are not perpendicular.

So the corret answer is:

a. -4; no