Help with trig question (1 Viewer)

[dabatman]

Hi

I have attached the question down below, the question asks you to simplify it

Thanks in advance

 

[pikachu975]

2cos^2 (3a) - 1 = cos6a from the identity cos2x = 2cos^2 x - 1

 

[jazz519]

Remember that cos2x=2cos^2(x)-1

So the thing simplifies to cos6alpha

 

[dabatman]

thanks guys