Bearings · Year 11
In Year 11 you learn: bearings with trigonometry.
A bearing gives a direction as an angle measured clockwise from north, always written with three figures. Bearings are used in navigation at sea, in the air and on land, and parallel north lines let you use angle facts to find back bearings.
Key facts
- Measure from north, clockwise.
- Always write three figures: 045°, not 45°.
- North 000°, east 090°, south 180°, west 270°.
- Back bearing: add 180° (or subtract 180° if the bearing is over 180°).
- The north lines at two points are parallel, so alternate and co-interior angles help.
Worked examples
Example 1
The angle between due east and the line AB is 35°, with B north of east. What is the bearing of B from A?
Answer: 055°
Example 2
The bearing of B from A is 070°. Find the bearing of A from B.
Answer: 250°
Example 3
A ship sails 8 km on a bearing of 040°, then 6 km on a bearing of 130°. How far is it from its start?
Answer: 10 km