Question

√12cos^2 5pi/12-√3=...​

Answer 1

$\sqrt{12}Cos^{2}\frac{5\pi }{12}-\sqrt{3} =2\sqrt{3}Cos^{2}\frac{5\pi }{12}-\sqrt{3} =\sqrt{3} (2Cos^{2}\frac{5\pi }{12}-1)=\\\\=\sqrt{3}Cos(2*\frac{5\pi }{12})=\sqrt{3}Cos\frac{5\pi }{6}=\sqrt{3}Cos(\pi-\frac{\pi }{6})=-\sqrt{3}Cos\frac{\pi }{6}=\\\\=-\sqrt{3}*\frac{\sqrt{3}}{2}=-\frac{3}{2}= -1,5 \\\\Otvet:\boxed{-1,5}$