Two important identities

They are very important and should be learnt. Generally you are not asked to prove them but just use them. They form the basis for many more other identities. In this video I explain how they are proved though.

Two Trigonometric Identities You Should Know | ExamSolutions - youtube Video

Proving trigonometric identities

Example 1

In the video I show you how to set out a trigonometric identity and prove it.
This is a tricky topic and one that I find students give in too quickly. Learn your formulae and have patience.

Proving Trigonometric Identities | ExamSolutions - youtube Video

Example 2

Another example to try, which reflects more methods.

Proving Trigonometric Identities | ExamSolutions - youtube Video

Example 3

Another example in the series which I would encourage you to try. Learn your formulae and have patience.

Proving Trigonometric Identities | ExamSolutions - youtube Video