Question

cos 105-cos 15/cos 315=Пазязяяя

Answer 1

$\frac{cos105-cos15}{cos315}=\frac{cos(180-75)-cos15}{cos(360-45)}=\frac{-cos75-cos15}{cos(-45)}\\\\=\frac{-(cos75+cos15)}{cos45}=-\frac{2cos45\cdot cos30}{cos45}=-2cos30=-2\frac{\sqrt3}{2}=-\sqrt3$