Question

Упростите: sin 87° - sin 93° - sin 59° + sin 61°

Answer 1

Sin87 - Sin93 - Sin59 + Sin61 = Sin(90 - 3) - Sin (90 + 3) - Sin59 + Sin61=
= Cos3 - Cos3 - (Sin59 - Sin 61) = - (Sin59 - Sin61)= -$2Sin frac{59-61}{2} Cos frac{59+61}{2}= 2Sin 1*Cos60=2Sin1* frac{1}{2} =Sin1$