Найдите значение функции при:

Решите задачу:

$y(- \frac{19\pi}{4} )= \frac{1}{[sin(- \frac{19\pi}{4} )]^2}= \frac{1}{[-sin( \frac{19\pi}{4} )]^2}= \frac{1}{[sin(\frac{16\pi+3\pi}{4} )]^2}=$
$= \frac{1}{[sin(2*2\pi+\frac{3\pi}{4} )]^2}= \frac{1}{[sin(\frac{3\pi}{4} )]^2}= \frac{1}{[sin( \frac{\pi}{2}+ \frac{\pi}{4} )]^2}= \frac{1}{[cos(\frac{\pi}{4} )]^2}= \frac{1}{ (\frac{ \sqrt{2} }{2})^2 } =2$