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  1. Trigonometry | Definition, Formulas, Ratios, & Identities | Britannica

    Dec 12, 2025 · Trigonometry, the branch of mathematics concerned with specific functions of angles. There are six functions commonly used in trigonometry: sine (sin), cosine (cos), …

  2. Trigonometry - Angles, Triangles, Sines | Britannica

    Dec 12, 2025 · Trigonometry - Angles, Triangles, Sines: A somewhat more general concept of angle is required for trigonometry than for geometry. An angle A with vertex at V, the initial …

  3. Trigonometric function | Definition, Formula, & Concepts | Britannica

    Dec 22, 2025 · A trigonometric function is one of the six functions (sine, cosine, tangent, cotangent, secant, and cosecant) that represents ratios of sides of right triangles.

  4. Tangent | Definition, Formulas, & Facts | Britannica

    Jan 2, 2026 · trigonometric function, in mathematics, one of the six functions (sine [sin], cosine [cos], tangent [tan], cotangent [cot], secant [sec], and cosecant [csc]) that represent ratios of …

  5. Cotangent | Definition, Formulas, & Facts | Britannica

    Jan 2, 2026 · In trigonometry, the tangent function (tan) of an angle in a right triangle is the ratio of the opposite side to the adjacent side.

  6. Secant | Definition, Formulas, & Facts | Britannica

    In trigonometry, the tangent function (tan) of an angle in a right triangle is the ratio of the opposite side to the adjacent side.

  7. Sine | Definition, Formulas, & Facts | Britannica

    sine, one of the six trigonometric functions, which, in a right triangle ABC, for an angle A, is sin A = length of side opposite angle A/ length of hypotenuse. (The other five trigonometric functions …

  8. Geometry | Definition, History, Basics, Branches, & Facts | Britannica

    Geometry, the branch of mathematics concerned with the shape of individual objects, spatial relationships among various objects, and the properties of surrounding space.

  9. Trigonometry - Angles, Triangles, Sines | Britannica

    Dec 12, 2025 · Trigonometric functions of a real variable x are defined by means of the trigonometric functions of an angle. For example, sin x in which x is a real number is defined to …

  10. Trigonometry - Angles, Triangles, Sines | Britannica

    Dec 12, 2025 · Trigonometry - Angles, Triangles, Sines: In the 16th century trigonometry began to change its character from a purely geometric discipline to an algebraic-analytic subject.