Question

Hello, can you please help me solve this question a, b and c !

Answer 1

Given:

We need to solve

`\cos ^4x-\sin ^4x`

Solution;

Now,

`\begin{gathered} \cos ^4x-\sin ^4x=(\cos ^2x)^2-(\sin ^2x)^2 \\ =(\cos ^2x-\sin ^2x)(\cos ^2x+\sin ^2x) \\ =(\cos 2x)(1) \\ =\cos 2x \end{gathered}`

So,the simpler form is

`\cos 2x`