Question

If vector A is added to vector B, the result is (6i + j). If B is subtracted from A, the
result is (-4i + 7j). What is the magnitude of A?

Answer 1

Explanation:

A + B = ( 6i + j) ------- 1

A - B = (-4i + 7j) ---------2

So adding eq 1 and 2 we get

2A = 2i + 8j

A = i + 4j

Using R = √A² + B² + 2AB cos(Φ)

we get

| A | = √ 1² + 4² + 2(1)(4) cos(90)

= √ 1 + 16

= √17

It must be correct.