Yes, I just call it "trig" because I always misspell trigonometry. Maybe you can use the double angle formula and you don't have a problem with trig identities.

Double angle formulas are named so because they involve trigonometric functions of double angles, i.e., sin2θ, cos2θ and tan2θ. There are three main double angle formulas as below: ...

Solve trigonometric equations in Higher Maths using the double angle formulae, wave function, addition formulae and trig identities.

sin x 4 = sin 75 ∘ 9 sin x = 4 × sin 75 ∘ 9 sin x = 0.429300. Do not round this answer yet. To calculate the angle use the inverse sin button on the calculator (sin 1). x = 25.4 ∘ ...