Trigonometry

Trigonometry is the study of triangles. Ancient builders and mariners used it to find lengths that were too large or inconvenient to measure directly, but could be determined by angles. Use these resources to develop a solid understanding of trigonometry and its practical applications.

1. Getting started
   • Pythagoras’ theorem
     Use this resource to learn how to use Pythagoras' theorem to find the lengths of the sides in a right-angled triangle.
   • Right-angled triangle trigonometry
     Use this resource to learn how to use trigonometric ratios to find unknown angles and lengths in right-angled triangles.
   • The sine rule
     Use this resource to learn what the sine rule is and how it is applied.
   • The cosine rule
     Use this resource to learn about the cosine rule, how it is applied to find unknown sides and angles, and its importance in solving complex geometric problems involving any type of triangle.
2. Next steps
   • Angular measurement and the unit circle
     Use this resource to learn about radians as a measure of angle.
   • Circular functions
     Use this resource to learn how the trigonometric ratios can be extended to angles greater than \(90^{\circ}\), using angles in a unit circle.
   • Solving trigonometric equations
     Use this resource to learn how to use the unit circle to find solutions for trigonometric equations.