

Rút gọn biểu thức:
[tex]a. A=\frac{1+2sin\alpha .cos\alpha }{cos^{2}\alpha -sin^{2}\alpha }[/tex]
[tex]b. B=(1+tan^{2}\alpha )(1-sin^{2}\alpha )-(1+cot^{2}\alpha )(1-cos^{2}\alpha )[/tex]
[tex]a. A=\frac{1+2sin\alpha .cos\alpha }{cos^{2}\alpha -sin^{2}\alpha }[/tex]
[tex]b. B=(1+tan^{2}\alpha )(1-sin^{2}\alpha )-(1+cot^{2}\alpha )(1-cos^{2}\alpha )[/tex]