ABSTRACT
This chapter states the theorem of Pythagoras and use it to find the unknown side of a right angled triangle, defines sine, cosine, tangent, secant, cosecant and cotangent of an angle in a right angled triangle and understands fractional and surd forms of trigonometric ratios. It evaluates trigonometric ratios of angles, solves right angled triangles, understands angles of elevation and depression and appreciates trigonometric approximations for small angles. Trigonometry is the branch of mathematics that deals with the measurement of sides and angles of triangles, and their relationship with each other. The easiest method of evaluating trigonometric functions of any angle is by using a calculator.
