Can someone help me please. I don't know which way to go with this.
Solve the equation
sin2x - 1 = cos 2x
giving answers for values of x between 0 and 360 degrees.
Here's a proof of the double angle formula for the sine and cosine functions so that you can better understand them.
sin 2α = sin (α + α)
sin 2α = sin α cos α + cos α sin α
sin 2α = 2 sin α cos α
So, there's two ways to substitute here. The question you have to ask yourself is which one will be more efficacious.