Bearings & Scale Drawings

Spec reference: Geometry and measures - Properties and constructions
Key idea: Measure and calculate bearings; use scale drawings and maps.

---

Bearings

A bearing is an angle measured:

• Clockwise from North
• Written as a 3-digit number (e.g. 045°, not 45°)

Examples

• Due East = 090°
• Due South = 180°
• Due West = 270°
• Due North = 000° or 360°

Back bearings

To find the bearing from B to A given the bearing from A to B:

• If bearing from A to B is less than 180°: add 180°
• If bearing from A to B is more than 180°: subtract 180°

---

Scale drawings and maps

$$\text{Real distance}=\text{Map distance}\times \text{scale}$$

Example

A map has scale 1 : 25,000. Two towns are 8 cm apart on the map.

Real distance $=8\times \mathrm{25,000}=\mathrm{200,000}$ cm $=\boxed{{\displaystyle 2\text{ km}}}$

---

Test Yourself

Question 1 of 5

Bearing for due East?