Question

даю 50 баллов 8 клас ​

Answer 1

$1)SinA=\sqrt{1-Cos^{2}A }=\sqrt{1-(\frac{\sqrt{2} }{2})^{2}} =\sqrt{1-\frac{2}{4}}=\sqrt{1-\frac{1}{2}}=\sqrt{\frac{1}{2}}=\boxed{\frac{\sqrt{2} }{2}} \\\\\\2)\frac{Cos^{2}\alpha}{(1-Sin\alpha)(1+Sin\alpha)}=\frac{Cos^{2}\alpha}{1-Sin^{2}\alpha} =\frac{Cos^{2}\alpha}{Cos^{2}\alpha}=\boxed1\\\\\\3)2Sin60^{0}+4Cos60^{0}-Ctg30^{0} -2tg45^{0}=2*\frac{\sqrt{3} }{2}+4*\frac{1}{2}-\sqrt{3}-2*1=\\\\=\sqrt{3}+2-\sqrt{3}-2=\boxed0$