Trigonometry Applications

Bearings

Use three-figure bearings measured clockwise from north to solve route and navigation problems.

Three-figure bearings

A bearing is measured clockwise from north and written with three digits, such as \(045^\circ\), \(120^\circ\) or \(305^\circ\).

Exam method

  1. Draw a north line at each relevant point.
  2. Mark the bearing clockwise from north.
  3. Look for parallel north lines and alternate/co-interior angles.
  4. Use sine rule, cosine rule or right-triangle trigonometry.
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For non-right-angle triangles, use the sine rule, cosine rule and area formula strategically.