Contents

Basic Identities

Second Degree Identities

Simple Equations

Second Degree Equations

Quiz 

Trigonometry Main Page

Basic Identities

Using the definitions we have learnt, we shall prove that 

tan q= sin q/ cos q, cos q ≠ 0

sin² q + cos² q = 1

cot q = cos q/ sin q , sin q ≠ 0

Proof: 

Also, by Pythagoras theorem, a² + b² = c² 

Example 

Given that cos q = 4/5, find the possible values of sin q and tan q

sin² q = 1 - cos² q

          = 1 - (4/5)²

          = 9/25

   sin q = ±3/5