cos 0 = 1; cos 90 = 0; cos 180 =- 1; cos 270 = 0; cos 360 = 1;
tan0 = 0tan 90 = 1; tan 180 = 0; tan 360 = 0; Tan270 does not exist, 270? Is not the domain of tan function.
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.
equation
Digital relation
tanαcotα= 1;
sinαCSCα= 1;
cosαsecα= 1;
Relationship of quotient
tanα=sinα/cosα cotα=cosα/sinα
Square relation
Sin? α+cos? Α= 1;
1+ Tan? α = seconds? Α;
1-cos? α= CSC? Α;
References:
Baidu encyclopedia trigonometric function value