Explanation

The direction of a vector is the angle it makes with the positive x-axis.

Formula:
θ = tan⁻¹(y / x)

Important:

• Angle is measured counterclockwise

• Must consider the quadrant

Example:
⟨3, 3⟩
θ = tan⁻¹(1) = 45°

Quiz

1. What does direction measure?

2. What trig function is used?

3. From which axis is direction measured?

4. What angle does ⟨1, 0⟩ have?

5. Is quadrant important?

Answer Key

1. Angle of the vector

2. Inverse tangent

3. Positive x-axis

4. 0°

5. Yes