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.
Proving trigonometric identities
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.
Another example to try, which reflects more methods.
Another example in the series which I would encourage you to try. Learn your formulae and have patience.