sin 36/sin 12 - sin 54/sin 78

Question

sin 36/sin 12 - sin 54/sin 78

Answer 1

sin 36/sin 12    -   sin 54/sin 78= (sin 36*sin78 - sin 54*sin 12)/sin 12*sin 78=

(cos 54*cos 12 - sin 54*sin 12)/sin12*cos 12=cos(54+12)/sin 24/2=2cos 66/sin 24=

2sin 24/sin 24=2

Ответ:2