Question

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Answer 1

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