Bearings

Key Facts and Exam Tips

A bearing is an angle measured in degrees clockwise from north. It is used to describe a direction. North is at 000º. A full turn is 360º.

Directions are stated as three-figure bearings. For example, 090º is east, 000º is north, 120º is between east and south-east.

To draw a bearing from a particular point, you often need to construct a north line at the point. The question will always show the direction of north. Your north line must be drawn parallel to the given line. Examination questions are often drawn on a grid, with the vertical grid lines running from north to south, to help you do this.

Once you have constructed a north line, use a protractor to measure the required angle. Remember to place 0º (the base-line of your protractor) along the north line, and the centre of the protractor on the point. Be as accurate as you can, and try to keep your protractor still while you are measuring.

Always measure the angle clockwise. The outside scale of a protractor usually runs clockwise.

Mark the angle with a sharp pencil, and use a ruler to draw the line from this mark to the point you measured from. The length of the line you need to draw will depend on the question. Usually you will need to work out the length in centimetres from the scale of the drawing and information given in the question.

Make all measurements as accurately as possible.

When measuring bearings, the wording of the question is important, particularly the word ‘from’. The bearing of B from A means that you should make your measurement from the point A.

To measure a bearing, draw the line between the two points. Construct a north line at the point from which the bearing is to be measured. Place your protractor over the point as described above. Measure clockwise around the protractor to the direction shown by the line joining your points.

You should learn the main compass points and their bearings. You can check an angle you have drawn or measured by considering where it should lie in relation to the compass points. For example, a bearing of 210º indicates a direction between south (180º) and west (270º), nearer to south than west.

If you know the bearing of B from A, the reverse bearing, or ‘back bearing’, is the bearing of A from B. It can represent the direction of a return journey. This can be calculated (using angle properties) or measured, depending on the question.

It is useful to know and understand the properties of alternate and corresponding angles (angles on parallel lines), supplementary angles (add up to 180º) and complementary angles (add up to 90º). These are often helpful when answering questions on trigonometry and Pythagoras’ Theorem that involve bearings.

Remember to state bearings as three figures even if the first figure is zero.

Always work clockwise from north. The 0º line on your protractor will be placed along the north line (usually vertically).

Always work to the scale given in the question and use the units stated.