Trigonometric Functions — Chapter Summary

A radian is the angle subtended

A radian is the angle subtended at the center of a circle by an arc equal in length to the radius. One complete revolution equals \(2\pi\) radians, wh

For any real number \(\theta\)

For any real number \(\theta\), the trigonometric functions are defined using a point \((x, y)\) on the unit circle (circle with radius 1). Specifical

These formulas express trigonometric functions

These formulas express trigonometric functions of sum or difference of angles in terms of functions of individual angles: \(\cos(A \pm B) = \cos A \co

Formulas like \(\sin 2A = 2\sin

Formulas like \(\sin 2A = 2\sin A \cos A\), \(\cos 2A = \cos^2 A - \sin^2 A\), and \(\tan 2A = \frac{2\tan A}{1 - \tan^2 A}\) express trigonometric fu

Unlike algebraic equations

Unlike algebraic equations, trigonometric equations have infinitely many solutions due to periodicity. The general solutions are: - \(\sin \theta = 0