In rectangular coordinate system, it is the trigonometric function of tan θ = y/x.
For any real number x, there is a unique angle (equal to this real number in the arc system), which corresponds to a unique tangent tanx. The function established according to this correspondence law is called tangent function. The tangent function in the form of f(x)=tanx is another trigonometric function different from sine function, and the biggest difference between it and sine function is the discontinuity of the definition domain.
Extended data:
Trigonometric function is a kind of transcendental function in elementary function in mathematics. Their essence is the mapping between the set of arbitrary angles and a set of ratio variables. The usual trigonometric function is defined in the plane rectangular coordinate system, and its domain is the whole real number domain.
The other is defined in a right triangle, but it is incomplete. Modern mathematics describes them as the limit of infinite sequence and the solution of differential equation, and extends their definitions to complex system. Because of the periodicity of trigonometric function, it does not have the inverse function in the sense of single-valued 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.
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