Which of followings is true for sin u cos v - cos u sin v

Which of followings is true for cos u cos v + sin u sin v

2 sin x cos x represents

cos²x - sin²x represents

2 cos²x - 1 represents

1 - 2 sin²x represents

 $\frac{2\tan x}{1\ -\ \tan^2\ x}$  represents

 $2\sin\left(\frac{x+y}{2}\right)\cos\left(\frac{x\ -y}{2}\right)\ =$  

 $2\cos\left(\frac{x+y}{2}\right)\cos\left(\frac{x\ -y}{2}\right)\ =$  

 $2\cos\left(\frac{x+y}{2}\right)\sin\left(\frac{x\ -y}{2}\right)\ =$  

 $-2\sin\left(\frac{x+y}{2}\right)\sin\left(\frac{x\ -y}{2}\right)\ =$  

 $\frac{b^2+c^2-a^2}{2bc}$  represents

 $\frac{c^2+a^2-b^2}{2ac}$  represents

 $\frac{b^2+a^2-c^2}{2ab}$  represents

 $\pm\frac{\sqrt{1-\cos2x}}{2}$  

 $\pm\frac{\sqrt{1+\cos2x}}{2}$  

 $\pm\frac{\sqrt{1-\cos2x}}{\sqrt{1+\cos2x}}$  

2 sinx siny = 

2 cosx cosy = 

2 sinx cosy = 

2 cosx siny  =