The trigonometric formula (or identity) should you use to help simplify and solve the equation is [tex]cos2x = 1-2sin^2x[/tex]
Given the trigonometry identity
According to trigonometry identity
Also since [tex]cos^2x = 1-sin^2x[/tex], the expression becomes;
[tex]cos2x = (1-sin^2x)-sin^2x\\ cos2x = 1- 2sin^2x[/tex]
To simplify the function given, you will substitute [tex]cos2x = 1-2sin^2x[/tex] into the original equation to have:
[tex] \cos(2x) - \sin(x) = 1\\ (1-2sin^2x)-sinx=1\\ [/tex]
Hence the trigonometric formula (or identity) should you use to help simplify and solve the equation is [tex]cos2x = 1-2sin^2x[/tex]
Learn more on trig identity here: https://brainly.com/question/24496175