Question

Quick question about trigonometric identities. I have trouble recalling what these mean:

Answer 1

How do you get \[\sin ^{2}x\] and how do you get \[\cos(2x)\]

Answer 2

If there is sinx.sinx that will equal \[\sin ^{2}x\]

Answer 3

or you use the equation \[\cos ^{2}x+\sin ^{2}x=1\]
and rearrange to equal \[\sin ^{2}x\]

Answer 4

You get cos2x from the equation cos(A+B)-cosAcosB-sinAsinB
And you let B=A
Which gives cos2A=cosAcosA-sinAsinA

Answer 5

Thanks @WilliamF

Answer 6

your welcome