Cot is cotangent in Chinese, and cot=cos/sin.

Sec is secant, sec= 1/cos.

Csc is called cotangent, csc= 1/sin.

First, cot (cotangent function)

1, cot is the symbol of cotangent trigonometric function in trigonometric function, which was previously written as ctg.

2.cot coordinate system indicates that cotθ=x/y, cotθ=cosθ/sinθ, θ=kπ, and cotθ =1/tan θ in trigonometric function (θ = kπ, and COT θ does not exist in k∈Z).

Second, sec (secant)

1, secant (seconds) is a trigonometric function.

2. Its domain is not a whole set of real numbers, and its range is real numbers with absolute value greater than or equal to 1. It is a periodic function with a minimum positive period of 2π.

3. Secant is one of the positive functions of trigonometric functions (sine, tangent, secant and vector), so the function is increasing in the range of 2kπ to 2kπ+π/2, and secant function and cosine function are reciprocal.

Third, csc.

1, the ratio of the hypotenuse of a right triangle to the opposite side of an acute angle is called the cotangent of an acute angle, which is expressed by csc (angle).

2. The quotient obtained by dividing the distance from the vertex of an angle to another arbitrary point on the terminal edge of the angle by the non-zero ordinate of the following point, the vertex of the angle coincides with the origin of the plane rectangular coordinate system, and its starting edge coincides with the positive direction of the X axis.

3. Write it as cscx, which is the reciprocal of the sine ratio expression. The function of cotangent is like odd function, which is a periodic function.

Related information:

Trigonometric function is a transcendental function in elementary functions in mathematics. Their essence is the mapping between any set of angles and a set of ratio variables. The usual trigonometric function is defined in a plane rectangular coordinate system. Its definition field is the whole real number field. 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.

The formulas of trigonometric functions seem to be many and complicated, but as long as we master the essence and internal laws of trigonometric functions, we will find that there is a strong connection between the formulas of trigonometric functions. And mastering the inherent law and essence of trigonometric function is also the key to learn trigonometric function well.