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Geometry and trigonometry · Subtopic 4 of 13

Bearings, Scale Drawings and Symmetry

A bearing is an angle measured clockwise from north, written with three figures. To reverse a bearing, add or subtract 180∘180^\circ. Map scales turn real distances into drawn ones, and symmetry describes how a shape fits onto itself.

Cambridge 4024 Paper 1Cambridge 4024 Paper 2Edexcel 4MA1 Papers 1H, 2HEdexcel 4MA1 Papers 1F, 2FAQA 8300 Papers 1–3≈ 25 minRevision 5 · updated 2026-10-27
Section 1 of 14

Learning objectives

  • Measure and write three-figure bearings, clockwise from north.
  • Find a back bearing (the bearing of AA from BB).
  • Convert between map distances and real distances using a scale.
  • Find lines of symmetry and the order of rotational symmetry of a shape.
Pause and think

You walk from home to school on a bearing of 070∘070^\circ. Which bearing takes you straight back home?

Section 2 of 14

Core idea

Start hereDirections at sea

At sea there are no roads to follow. Sailors give directions as angles from north: "steer 060" means 60∘60^\circ clockwise from north. Combine bearings with distances and trigonometry, and you can plot any course.

The big idea

Bearing: clockwise from north, three figures (060∘060^\circ). Back bearing: ±180∘\pm180^\circ.

1. Bearings

The bearing of B from A is 060°
NN60°240°AB
From A, turn 60∘60^\circ clockwise from north to face B. The back bearing from B to A is 60∘+180∘=240∘60^\circ+180^\circ=240^\circ.
Worked exampleA ship's course

8 km on 060∘060^\circ, then 6 km on 150∘150^\circ.

Goal
Distance and bearing from the start.
Strategy
Find the angle at the turn, then Pythagoras and tan.
  1. back bearing=240∘\text{back bearing}=240^\circ
    60+18060+180: direction back to the start.
  2. 240−150=90∘240-150=90^\circ
    Angle at the turn: right-angled.
  3. 64+36=10 km\sqrt{64+36}=10\text{ km}
    Pythagoras.
  4. tan⁡−168=36.9∘⇒060+36.9=096.9∘\tan^{-1}\tfrac68=36.9^\circ\Rightarrow060+36.9=096.9^\circ
    Angle at the start added to the first bearing.
Answer1010 km on 096.9∘096.9^\circ.
✓ CheckBetween 060∘060^\circ and 150∘150^\circ ✓.
Common misconceptionTwo-figure bearings Write 060∘060^\circ, not 60∘60^\circ.

2. Symmetry

Symmetry of a regular hexagon: 6 lines, order 6
A regular nn-sided polygon has nn lines of symmetry and rotational symmetry of order nn.
  • Line symmetry: fold to match.
  • Rotational order: how many times it fits in a full turn.
Pause and think

Bearing of A from B is 300∘300^\circ. Bearing of B from A?

Summary

  • Clockwise from north, 3 figures.
  • Back bearing ±180°.
Key words
Bearing
Direction as an angle from north.
HistoryThe compass rose. Medieval sailors used a "compass rose" with 3232 named points such as north-north-east. The magnetic compass had reached Europe from China by the 1100s. Three-figure bearings in degrees replaced named points because one number is far harder to mishear over a radio.
Fun factRunways are bearings. The big number painted at the end of an airport runway is its bearing divided by 1010. A runway marked 2727 points roughly west (270∘270^\circ); the other end of the same strip is marked 0909, the back bearing.
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