Trig Identities Worth Memorizing
The Pythagorean, reciprocal, quotient, double-angle and sum identities, how to use them to find exact values, and a method for proving identities.
Geometry & Trig
Area and volume, the Pythagorean theorem, circles, similar triangles and trigonometry from SOH CAH TOA to the unit circle and the laws of sines and cosines.
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The Distance and Midpoint Formulas
How to find the distance between two points and the midpoint of a segment, where the formulas come from, and how to find an endpoint from a midpoint.
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Solving Any Triangle With the Law of Sines and Law of Cosines
When to use the law of sines or the law of cosines, how to solve triangles that are not right triangles, the ambiguous case, and the SAS area formula.
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Similar Triangles and Missing Sides
What makes triangles similar, the AA, SAS and SSS similarity tests, how to set up proportions for missing sides, and how area and perimeter scale.
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Circle Formulas, From Area to the Equation of a Circle
Every circle formula you need: circumference, area, arc length, sector area in degrees and radians, inscribed angles, and the equation (x − h)² + (y − k)² = r².
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Getting Comfortable With the Unit Circle
Learn the unit circle: radians, the first-quadrant values, reference angles, signs in each quadrant, tangent, coterminal angles and the Pythagorean identity.
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Area, Surface Area and Volume, With Worked Problems
Every common area, surface area and volume formula in one place, plus composite shapes, unit conversions, scaling, and real-world problems with full solutions.
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The Pythagorean Theorem, With Real Examples
Use a² + b² = c² to find a missing side, test whether a triangle is right, find distances on a graph, and recognize triples and special right triangles.
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SOH CAH TOA and Right-Triangle Trigonometry
How sine, cosine and tangent work in a right triangle, how to find a missing side or angle, angles of elevation, exact values, and complementary angles.