Introduction…

The study of angles and of the angular relationships of planar and three-dimensional figures is known as trigonometry. The trigonometric functions (also called the circular functions) comprising trigonometry are the cosecant , cosine  cotangent , secant , sine , and tangent .

The inverses of these functions are denoted with a power of -1. This is used to find the angle of the triangle.  However, in secondary 2, there will only be a need to learn tangent, sine and cosine.