Question

Cos 64°cos4°-sin4°sin 64°/cos 71°cos41°+sin41°sin71°

Answer 1

$\frac{cos64*cos4+sin4*sin64}{cos71*cos41+sin41sin71}= \frac{cos(64-4)}{cos(71-41)}= \frac{cos60}{cos30}= \frac{1}{2}* \frac{2}{ \sqrt{3}}= \frac{1}{ \sqrt{3}}$