Question

Нужно просто решить.

Answer 1

Объяснение:

$5)\ \frac{sin54^0-sin36^0}{sin9^0}=\frac{sin54^0+sin(-36^0)}{sin9^0} =\frac{2*sin\frac{54^0+(-36^0)}{2} *cos\frac{54^0-(-36^0)}{2} }{sin9^0} =\\=\frac{2*sin9^0*cos45^0}{sin9^0} =2*\frac{\sqrt{2} }{2}=\sqrt{2}.$

$6)\ \frac{cos46^0-cos74^0}{sin14^0}=\frac{2*sin60^0*sin14^0}{sin14^0}=2*\frac{\sqrt{3} }{2} =\sqrt{3}.$

$7)\ \frac{cos78^0-cos12^0}{sin78^0-sin12^0} =\frac{2*sin45^0*sin(-32^0)}{2*sin32^0*cos45^0} =-\frac{\frac{\sqrt{2} }{2}*sin32^0 }{sin32^0*\frac{\sqrt{2} }{2} }=-1.$