# Trigonometric equations and identities

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Evaluate inverse trig functions

Solve sinusoidal equations (basic)

Solve sinusoidal equations

Sinusoidal models word problems

Using the trig angle addition identities

Contents

Learn about the inverse functions of sine, cosine, and tangent, and how they are defined even though the functions are not really invertible. These functions will be very helpful when you will solve trigonometric equations.

Learn how to solve equations of the form sin(x)=d or cos(x)=d where d is any number. For example, solve sin(x)=0.6.

Learn how to solve equations of the form a*sin(bx+c)=d or a*cos(bx+c)=d where a, b, c, and d are any number. For example, solve 5*sin(2x-1)=3.

Solve word problems that involve sinusoidal modeling functions.

Learn about the trigonometric angle addition identities, which help us discuss the trig values of sums of angles in terms of the trig values of the individual angles. For example, we can express sin(x+y) in terms of sin(x), sin(y), cos(x), and cos(y).

Learn about different ways in which trigonometric identities, such as the Pythagorean identity and the angle addition identities, can be used to solve problems.

See Sal solve a bunch of very challenging geometry and algebra problems that involve trigonometry.