Copyright © University of Cambridge. All rights reserved.

'Trig Identity' printed from https://nrich.maths.org/

Show menu

 

 

In this diagram $O$ is the centre of a unit circle (i.e. a circle with radius 1).

Use it to find two trigonometrical relationships between $A$ and $2A$.

 
 
 

 

Did you know ... ?

Trigonometrical expressions can often be derived algebraically or geometrically. In more advanced applications the functions of trigonometry are defined as infinite power series rather than geometric ratios.