Take angle a as an example, so there are:
(1) Sina: Sine. The ratio of the opposite side to the hypotenuse of angle A, sina = a/c.
(2)cosA: stands for cosine. The ratio of the straight edge adjacent to the angle A to the hypotenuse, COSA = b/c.
(3) Tana: it means tangent. The ratio of the opposite side of angle A to the adjacent straight side, tana = a/b.
Sine? Cosine? And then what? Tangent? (English symbol abbreviated as? Sin? Because? And then what? Tan) is the ratio of each side of a right triangle, as shown in the following figure:
trigonometric function
Common trigonometric functions are sine function, cosine function and tangent function. Other trigonometric functions, such as cotangent function, secant function, cotangent function, dyadic function, cofactor function, semidyadic function and semifactorial function, are also used in other disciplines, such as navigation, surveying and engineering. The relationship between different trigonometric functions can be obtained by geometric intuition or calculation, which is called trigonometric identity.
Trigonometric functions are generally used to calculate the sides and angles of triangles with unknown lengths, and are widely used in navigation, engineering and physics. In addition, taking trigonometric functions as templates, we can define a class of similar functions, which are called hyperbolic functions. Common hyperbolic functions are also called hyperbolic sine functions, hyperbolic cosine function and so on.