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## Homework Statement

Scalar product of vectors

**AB**= -6; vector product of

**AB**= 9. Find the angle between vectors

**A**and

**B**.

## Homework Equations

Scalar product: cos(θ)*AB

Vector product: sin(θ)*AB

(sin(θ))/cos(θ) = tanθ

## The Attempt at a Solution

AB = -6/cos(θ)

AB = 9/sin(θ)

9/sin(θ) = -6/cos(θ)

9/-6 = (sin(θ))/cos(θ)

3/-2 = tan(θ)

tan^-1(3/-2) = -56° which I take to mean 56° from each other.

But their answer is 124° which is -56° + 180°. How can this be when the whole time we are dealing with one angle between two vectors?