Bearings

#### Tier: #Foundation #Higher

Description

A bearing is a direction measured clockwise from North, always written as a three-figure number (e.g. 045°, not 45°).

Three rules to remember:

1. Always measure from North
2. Always measure clockwise
3. Always write using three figures (pad with a leading zero if needed)

Example: Due East is a bearing of 090°. Due South is 180°. Due West is 270°.

Back bearings: if the bearing from $A$ to $B$ is $\theta$, the bearing from $B$ back to $A$ is $\theta + 180°$ (if $\theta < 180°$) or $\theta - 180°$ (if $\theta \geq 180°$).

Bearing problems often involve scale drawings or trigonometry (SOHCAHTOA, sine rule, cosine rule) to find distances or unknown angles.

Common error: measuring anticlockwise, or forgetting the three-figure rule and writing 45° instead of 045°.

Links

Angle facts Sine rule Cosine rule