Question

аааа сделайте пж....

Answer 1

$\displaystyle\bf\\5)\\\\\frac{Sin5\alpha -Sin\alpha }{Cos3\alpha } =\frac{2Sin\dfrac{5\alpha -\alpha }{2} Cos\dfrac{5\alpha +\alpha }{2} }{Cos3\alpha } =\frac{2Sin2\alpha Cos3\alpha }{Cos3\alpha } =2Sin2\alpha \\\\\\6)\\\\Sinx=\frac{1}{2} \\\\\\x=(-1)^{n} arcSin\frac{1}{2} +\pi n,n\in Z\\\\\\x=(-1)^{n}\frac{\pi }{6} +\pi n,n\in Z\\\\\\7)\\\\Cos\frac{x}{2} =-\frac{1}{2} \\\\\\\frac{x}{2} =\pm \ arcCos\Big(-\frac{1}{2} \Big)+2\pi n,n\in Z$

$\displaystyle\bf\\\frac{x}{2} =\pm \ \frac{2\pi }{3}+2\pi n,n\in Z\\\\\\x=\pm \ \frac{4\pi }{3} +4\pi n,n\in Z$