Trigonometric Functions in Right Triangle. Values of the trigonometric functions for any angle. Trigonometric identities. Angular measure of angle. Definition of trigonometric function of any angle. Signs of the trigonometric functions in four quadrants. Trigonometric functions of sum and difference of two angles. Trygonometric reduction formulas. Sum and difference of the trigonometric functions. Graph of the function y = sin x. Graph of the function y = cos x. Graph of the function y = tan x. Graph of the function y = tan x.