1.cos(π7)cos(2π7)cos(4π7)=\cos \left(\frac{\pi}{7}\right) \cos \left(\frac{2\pi}{7}\right) \cos \left(\frac{4\pi}{7}\right) =cos(7π)cos(72π)cos(74π)=a.−18\frac{-1}{8}8−1b.18\frac{1}{8}81c.−338\frac{-3\sqrt{3}}{8}8−33d.1Login to continueOnly logged in users canattempt or see the solution.
