Chapter Four Overview

 The sine definition basically says that, on a right triangle, the following measurements are related the measurement of one of the non-right angles, the length of the side opposite to that angle and the length of the triangle's hypotenuse. Alternately, the cosine definition basically says that, on a right triangle, the following measurements are related: the measurement of one of the non-right angles, the length of the side adjacent to that angle and the length of the triangle's hypotenuse. Therefore cosine equals adjacent over hypotenuse and sine equals opposite over hypotenuse. In chapter four we examine conditional trigonometric equations, that is, equations that are true for only certain values of the variable. When solving for the solutions for these equations there might be an infinite amount of answers because of the periodicity of the trigonometric functions. Also, to verify a trigonometric identity we use the fundamental trigonetric identities, the even-odd properties, and the basic arithmetic and algebraic operations. In order to verify a trigonometric identity, we are required to show that the given expressions are equivalent.