We urge all scholars to understand these formulas and then easily apply them to solve the various types of Trigonometry problems. These formulas are what simplifies the sides of triangles so that you can easily measure all their sides. Just like any other branch of mathematics, the formulas of Trigonometry are equally important, since without these formulas you can’t put the values of triangles for the measurement purpose. Domain and Range of Inverse Trigonometry Functions So, By this, you can see that Sin is an angle, Same as Inverse of all Trignomentry function is an angle. ABC are the vertices of the triangle ABC.