Помогите с геометрией :номер 147 буквы в,г

[latex]147. B) sin2xcos2x = - dfrac{1}{4} \ 0,5sin4x = - dfrac{1}{4} \ \ sin4x = - dfrac{1}{2} \ \ 4x = (-1)^{n + 1} dfrac{ pi }{6} + pi n, n in Z \ \ x = (-1)^{n+1} dfrac{ pi }{24} + dfrac{ pi n}{4}, n in Z \ \ \ r) sin dfrac{x}{3} cos dfrac{ pi }{5} - cos dfrac{x}{3}sin dfrac{ pi }{5} = dfrac{ sqrt{2}}{2} \ \ sin( dfrac{x}{3} - dfrac{ pi }{5} ) = dfrac{ sqrt{2}}{2} \ \ dfrac{x}{3} - dfrac{ pi}{5} = (-1)^n dfrac{ pi }{4} + pi n, n in Z \ [/latex][latex] dfrac{x}{3} = (-1)^n dfrac{ pi }{4} + dfrac{ pi}{5} + pi n, n in Z \ \ x = (-1)^n dfrac{ 3pi }{4} + dfrac{3 pi}{5} +3 pi n, n in Z.[/latex]