Trigonometry
Solve the following equation for x if x lies in the interval[0,π8]\left[0,\frac{\pi}{8}\right\rbrack[0,8π] .
y=−4cos8xy=-4\cos8xy=−4cos8x
x=18cos−1(y4)x=\frac18\cos^{-1}\left(\frac{y}{4}\right)x=81cos−1(4y)
x=8cos−1(y4)x=8\cos^{-1}\left(\frac{y}{4}\right)x=8cos−1(4y)
x=8cos−1(−4y)x=8\cos^{-1}\left(-4y\right)x=8cos−1(−4y)
x=18cos−1(−y4)x=\frac18\cos^{-1}\left(-\frac{y}{4}\right)x=81cos−1(−4y)