Trigonometric Functions（三角函数之歌） - Cc7oo
Composed by：Cc7oo
Sine cosine secant cosecant
Let's sing a song about trig-functions
Sin（2π+α）=sinα
Cos（2π+α）=cosα
Tan（2π+α）=tanα
Induction formula1 and induction formula 2
Sin（π+α）= -sinα
Cos（π+α）=-cosα
Tan（π+α）= tanα
Sin（π-α）= sinα
Cos（π-α）=-cosα
You wanna measure width of a river height of a tower
You scratch your head which cost you more than an hour
You don't need to ask any"gods" or" master" for help
This group of formulas are gonna help you solve
Sin(α+β)=sinα•cosβ+cosα•sinβ
Cos(α+β)=cosα•cosβ-sinα•sinβ
Tan(α+β)=(tanα+tanβ)/(1-tanα•tanβ)
Sin(α-β)=sinα•cosβ-cosα•sinβ
Cos(α-β)=cosα•cosβ+sinα•sinβ
Tan(α-β)=(tanα-tanβ)/(1+tanα•tanβ)
As you come across a right triangle you fell easy to solve
But an obtuse triange gonna make you feel confused
Don't worry about what you do
There are always means to solve
As long as you master the sine cosine law
At this moment I've got nothing to say
As trig-functions rain down upon me
At this moment I've got nothing to say
Let's sing a song about trig-functions
Long live the trigonometric functions
