Question

(1/cos^2a)-1
1-sin^2a+(sin^2a/tg^2a)
(sina+cosa)^2+(sina-cosa)^2

То, что после ^ - степень! a - альфа!

Answer 1

$1)\frac{1}{Cos^{2}\alpha}-1=\frac{1-Cos^{2}\alpha}{Cos^{2}\alpha}=\frac{Sin^{2}\alpha}{Cos^{2}\alpha}=tg^{2}\alpha\\\\2)1-Sin^{2}\alpha+\frac{Sin^{2} \alpha}{tg^{2}\alpha}=Cos^{2}\alpha+\frac{Sin^{2}\alpha}{\frac{Sin^{2}\alpha}{Cos^{2}\alpha} }=Cos^{2}\alpha+\frac{Sin^{2}\alpha*Cos^{2}\alpha}{Sin^{2}\alpha}=Cos^{2}\alpha+Cos^{2}\alpha=2Cos^{2}\alpha$

$3)(Sin\alpha+Cos\alpha)^{2}+(Sin\alpha-Cos\alpha)^{2}=Sin^{2}\alpha+2Sin\alpha Cos\alpha +Cos^{2}\alpha+Sin^{2}\alpha-2Sin\alpha Cos\alpha+Cos^{2}\alpha=2Sin^{2}\alpha +2Cos^{2}\alpha=2(Sin^{2}\alpha +Cos^{2}\alpha)=2*1=2$