View source for Trigonometry

The branch of geometry in which the metric relationships between the elements of a triangle are described in terms of trigonometric functions (see, e.g., [[Cosine theorem|Cosine theorem]]; [[Sine theorem|Sine theorem]]; [[Tangent formula|Tangent formula]]), as well as formulas relating the trigonometric functions (so-called goniometry) are established. Trigonometry is considered both in Euclidean and [[Non-Euclidean geometries|non-Euclidean geometries]]. The trigonometry of a sphere in Euclidean space is called [[Spherical trigonometry|spherical trigonometry]].



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Cf. also [[Plane trigonometry|Plane trigonometry]].