Trigonometry - Bearing

Bearings

• Bearings are a way of describing and using directions as angles

• To answer a question involving drawing bearings the following steps may help:

  • STEP 1: Draw a diagram adding in any points and distances you have been given

  • STEP 2: Draw a North line (arrow pointing vertically up) at the point you wish to measure the bearing from

    • If you are given the bearing from A to B draw the North line at A

  • STEP 3: Measure the angle of the bearing given from the North line in the clockwise direction

  • STEP 4: Draw a line and add the point B at the given distance

Elevation & Depression

If a person looks at an object that is not on the same horizontal line as their eye-level they will be looking at either an angle of elevation or depression

Diagram Drawing Techniques

• Make sure you know your compass directions

  • Due east means on a bearing of 090°

    • Draw the line directly to the right

  • Due south means on a bearing of 180°

    • Draw the line vertically downwards

  • Due west means on a bearing of 270°

    • Draw the line directly to the left

  • Due north means on a bearing of 360° (or 000°)

    • Draw the line vertically upwards

Example for Diagram

A city at B is due east of a city at A and A is due north of a city at E. A city at C is due south of B.

The bearing from A to D is 155° and the bearing from D to C is 30°.

The distance AB = 50 km, the distances BC = CD = 30 km and the distances DE = AE = 40 km.

Draw and label a diagram to show the cities A, B, C, D and E and clearly mark the bearings and distances given.