Solving trig equations

[gumballmaster24]

I have three problems i cant figure out! plase help me!

1. cos2x=cosx

2. cosx^2-sinx^2=1

3. cosx=secx=2


Please im freaking out!

 

[tkhunny]

3. cos(x) never is 2. That was easy.

2. \(\displaystyle \cos^{2}(x) + \sin^{2}(x) = 1\) -- Combine with that and see where it leads.

1. Three versions of cos(2x). Pick the right one and you are on your way. x = 2pi comes to mind right away.