"sin" is sine in mathematics, the sum of squares of sin and tan is 1, and sin is divided by cos to get tan, which ranges from positive infinity to negative infinity. So love, like a function, has unspeakable magic.
Introduction of trigonometric 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. Modern mathematics describes them as the limit of infinite sequence and the solution of differential equation, and extends their definitions to complex system.
Reference to the above content: Baidu Encyclopedia -Sine