Giá trị lượng giác của các góc có liên quan đặc biệt !!

A.$\cot \left(\pi -\alpha \right)=\cot \left(\pi +\alpha \right)$

B.$\cot \left(\frac{\pi }{2}-\alpha \right)=\tan \left(\pi +\alpha \right)$

C.$\cot \left(\pi +\alpha \right)=\cot \left(-\alpha \right)$

D.$\cot \left(\pi +\alpha \right)=\cot \left(\frac{\pi }{2}-\alpha \right)$

A.$\sin \left(\pi -\alpha \right)=\sin \left(\pi +\alpha \right)$

B.$\sin \left(\frac{\pi }{2}-\alpha \right)=\sin \left(\pi +\alpha \right)$

C.$\sin \left(\pi +\alpha \right)=\sin \left(-\alpha \right)$

D.$\sin \left(\pi +\alpha \right)=\cos \left(\frac{\pi }{2}-\alpha \right)$

A.$\tan \left(\pi -\alpha \right)=tan\left(\frac{\pi }{2}-\alpha \right)$

B.$tan\left(\frac{\pi }{2}-\alpha \right)=\tan \left(-\alpha \right)$

C.$tan\left(\pi -\alpha \right)=tan\left(\frac{\pi }{2}+\alpha \right)$

D.$tan\left(\frac{\pi }{2}-\alpha \right)=\cot \left(\pi +\alpha \right)$

A.$\tan \left(\pi +\alpha \right)=-tan\alpha$

B.$tan\left(-\alpha \right)=-\tan \left(\alpha \right)$

C.$tan\left(\frac{\pi }{2}-\alpha \right)=\cot \left(\alpha \right)$

D.$tan\left(\pi -\alpha \right)=-tan\left(\alpha \right)$

A.$\sin \frac{A+B}{2}=\sin \frac{C}{2}$

B.$\cos \frac{A+B}{2}=\cos \frac{C}{2}$

C.$\sin \left(A+B\right)=\sin C$

D.$\cos \left(A+B\right)=\cos C$

A.$A=\cos \alpha +\sin \alpha$

B.$A=2\sin \alpha$

C.$A=\sin \alpha -\cos \alpha$

D.A = 0

C. 2

A.$\sin 225°=\frac{-\sqrt{2}}{2}$

B.$\cos 225°=-\frac{\sqrt{2}}{2}$

C.$\tan 225°=-1$

D.$\cot 225°=1$

C. 0

A.$-\frac{1}{3}$

B.$\frac{1}{3}$

C.$\frac{2}{3}$

D.$-\frac{2}{3}$

A. S = 1

C. S = sin²x – cos²x

A.$\cos \frac{B+C}{2}=\sin \frac{A}{2}$

B.$\sin \left(A+C\right)=-\sin B$

C.$\cos \left(A+B+2C\right)=-\cos C$

D.$\cos \left(A+B\right)=-\cos C$

C. I và II