According to the inquiry subject network, trigonometric identity transformation is the compulsory content in the first volume of the A version (20 19) of mathematics teaching in senior one last semester. The fifth chapter, the chapter name is simple trigonometric identity transformation.

Trigonometric identity transformation is a simple identity transformation using sine, cosine, tangent formula and half-angle formula of the sum and difference of two angles, which is located at the junction of trigonometric function and mathematical transformation.