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The six trigonometric ratios, their values at standard angles, and the three identities.
Introduction to Trigonometry
Derive the exact trigonometric ratios of 0, 30, 45, 60 and 90 degrees from simple triangles, learn the full table with its not-defined entries, and use it to evaluate expressions and find unknown angles.
Introduction to Trigonometry
Learn what sine, cosine, tangent and their reciprocals mean in a right triangle, why they depend only on the angle, and how to find all six ratios when one is given, with six worked examples.