Question

неравенство sin2x*sinx-cos2x*cosx1/2

Answer 1

sin2x*sinx-cos2x*cosx1/2

1/2(2 sin(x) sin(2x)-cos(x)cos(2x))

-1/2 cos(x)(3cos(2x)-2)

1/4(cos(x)-3cos(3x))

 

$x=pi n - frac{pi }{2},$   n Е Z

$x=2pi n-+2 tan^{-1}(frac{1}{sqrt{11+2sqrt{30}}}),$  n Е Z

$x=2pi n-+2 tan^{-1}(sqrt{11+2sqrt{30}}),$  n Е Z