# Trigonometry with Bearings

# Trigonometry with Bearings Revision Content

**Understanding Bearings**

- Bearings are used in navigation to define the direction of one point relative to another. They are measured in degrees from the North line in a clockwise direction, typically expressed as a three-figure bearing.
- Always remember that bearing measurements should be between 0 and 360 degrees.

**Basic Principles**

- When reading or writing bearings, remember that a bearing must be a three-figure measurement. For example, “60°” would be written as “060°”.
- Be aware that bearings are always measured clockwise.

**Calculating Bearings in Trig Problems**

- To find the bearing, you can use basic geometry (usually involving right-angled triangles) and trigonometry. The cosine rule, sine rule or Pythagoras’ theorem might also be used, depending on the problem.
- Remember that sine, cosine, and tangent apply to right-angled triangles -
**sin = opposite/hypotenuse**,**cos = adjacent/hypotenuse**, and**tan = opposite/adjacent**. - You may also use these equations backwards to find angles, using the inverse functions sin^(-1), cos^(-1), and tan^(-1).

**Applied Examples**

- The angle of depression or elevation can be calculated using trigonometry when working with bearings and height problems.
- When asked to calculate a bearing, always remember to give your answer as a three figure bearing (claim to the nearest degree).