高中学的三角函数的各种关系式子

诱导公式

* sin(-a)=-sin(a)
* cos(-a)=cos(a)
* sin(pi/2-a)=cos(a)
* cos(pi/2-a)=sin(a)
* sin(pi/2+a)=cos(a)
* cos(pi/2+a)=-sin(a)
* sin(pi-a)=sin(a)
* cos(pi-a)=-cos(a)
* sin(pi+a)=-sin(a)
* cos(pi+a)=-cos(a)
* tgA=tanA=sinA/cosA

两角和与差的三角函数

* sin(a+b)=sin(a)cos(b)+cos(α)sin(b)
* cos(a+b)=cos(a)cos(b)-sin(a)sin(b)
* sin(a-b)=sin(a)cos(b)-cos(a)sin(b)
* cos(a-b)=cos(a)cos(b)+sin(a)sin(b)
* tan(a+b)=(tan(a)+tan(b))/(1-tan(a)tan(b))
* tan(a-b)=(tan(a)-tan(b))/(1+tan(a)tan(b))

三角函数和差化积公式

* sin(a)+sin(b)=2sin((a+b)/2)cos((a-b)/2)
* sin(a)−sin(b)=2cos((a+b)/2)sin((a-b)/2)
* cos(a)+cos(b)=2cos((a+b)/2)cos((a-b)/2)
* cos(a)-cos(b)=-2sin((a+b)/2)sin((a-b)/2)

积化和差公式

* sin(a)sin(b)=-1/2*[cos(a+b)-cos(a-b)]
* cos(a)cos(b)=1/2*[cos(a+b)