cos-3x-4-pi-sin-pi-4-2x-x-0-pi-

Question Number 92461 by jagoll last updated on 07/May/20

\cos (\frac{3 x}{4} - π) = \sin (\frac{π}{4} - 2 x)

x \in [0, π]

Commented by john santu last updated on 07/May/20

- \cos (\frac{3 x}{4}) = \sin (\frac{π}{4} - 2 x)

\cos (\frac{3 x}{4}) = \sin (2 x - \frac{π}{4})

\cos (\frac{3 x}{4}) = \cos (\frac{π}{2} + \frac{π}{4} - 2 x)

{\begin{cases} \frac{11 x}{4} = \frac{3 π}{4} + 2 k π \\ - \frac{5 x}{4} = - \frac{3 π}{4} + 2 k π \end{cases}

{\begin{cases} x = \frac{3 π}{11} + \frac{8 k π}{11} \\ x = \frac{3 π}{5} - \frac{8 k π}{5} \end{cases}