Question

2 cos(2пи-а)-sin(3пи2-2)+2sin(а+ 3пи2), если cos=- 0,5

Answer 1

$2Cos(2 pi - alpha )-Sin( frac{3 pi }{2}- alpha )+2Sin( alpha + frac{3 pi }{2} )=2Cos alpha +Cos alpha -$$2Cos alpha =Cos alpha =-0,5$