Trigonometry

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Trigonometry with right triangles

Learn the basics of trigonometry: What are sine, cosine, and tangent? How can we use them to solve for unknown sides and angles in right triangles?
Introduction to the trigonometric ratios
Solving for a side in a right triangle using the trigonometric ratios
Solving for an angle in a right triangle using the trigonometric ratios
Modeling with right triangles
Trigonometric ratios and similarity
Sine and cosine of complementary angles
Trigonometric ratios of special triangles
Introduction to the Pythagorean trigonometric identity
The reciprocal trigonometric ratios

Trigonometry with general triangles

Learn how to use trigonometry in order to find missing sides and angles in any triangle.
The law of sines
The law of cosines
Solving general triangles

The unit circle definition of sine, cosine, and tangent

Learn how the trigonometric ratios are extended to all real numbers using algebra. Start solving simple problems that involve this new definition of the trigonometric functions.
Introduction to radians
The unit circle definition of sine, cosine, and tangent
The graphs of sine, cosine, and tangent
Basic trigonometric identities
Trigonometric values of special angles
The Pythagorean identity
Long live Tau

Graphs of trigonometric functions

Learn how to graph trigonometric functions and how to interpret those graphs. Learn how to construct trigonometric functions from their graphs or other features.
The graphs of sine, cosine, and tangent
Introduction to amplitude, midline, and extrema of sinusoidal functions
Finding amplitude and midline of sinusoidal functions from their formulas
Period of sinusoidal functions
Graphing sinusoidal functions
Constructing sinusoidal functions

Trigonometric equations and identities

Learn how to solve trigonometric equations and how to use trigonometric identities to solve various problems.
The inverse trigonometric functions
Solving basic sinusoidal equations
Solving advanced sinusoidal equations
Solving sinusoidal models
Introduction to the trigonometric angle addition identities
Using trigonometric identities to solve problems
Challenging trigonometry problems

Staff picks

Trig identity reference
Proof of the law of sines
Unit circle
Solve for a side in right triangles
Graph of y=sin(x)

Review articles

Trig unit circle review
Laws of sines and cosines review
Pythagorean identity review
Midline, amplitude, and period review
Trigonometric ratios review

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Introduction to the trigonometric ratios
Meet your new best friends: sine, cosine, and tangent.
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