Question

Sorry its sideways :)​

Answer 1

(√6 - √2) / 4

Explanation:

cos(x+y) = cosx siny - sinx cosy

cos(75°) = cos(30°+45°) = cos30° sin45° -sin30°cos45°

= √3/2 * √2/2 - 1/2 * √2/2

=(√6 - √2) / 4