[tex]sin^{4} x+cos^{4} x= (sin^{2} x+cos^{2} x)^{2} - 2sin^{2} xcos^{2} x=1-2sin^{2} xcos^{2} x[/tex]
[tex]1-2sin^{2} xcos^{2} x=5/8
[/tex]
[tex]sin^{2} xcos^{2} x=3/16[/tex]
[tex]2sin^{2} xcos^{2} x=0,5*sin^{2} 2x[/tex]
[tex]sin^{2} 2x=3/8[/tex]
Вам дальше расписать?
[tex]sin2x= \sqrt{3/8} [/tex] (1)
[tex]sin2x=- \sqrt{3/8} [/tex] (2)
из (1): [tex]x= \frac{1}{2} (-1)^{n} arccsin \sqrt{3/8} + \frac{1}{2}\pi n[/tex]
из (2):[tex]x= \frac{1}{2} (-1)^{n} arccsin- \sqrt{3/8} + \frac{1}{2}\pi n[/tex]
