х=30
Объяснение:
cos2*30=cos60=1/2
cos(2x)=1/2
cos(2π-2x)=1/2
2x=arccos(1/2)
2π-2x=arccos(1/2)
2x=π/3
2π-2x=π/3
2x=π/3+2kπ,k€z
2π-2x=π/3+2kπ,k€z
x=π/6+kπ,k€z
x=5π/6-kπ,k€z
x=π/6+kπ,k€z
x=5π/6+kπ,k€z
x={π/6+kπ ; 5π/6+kπ
альтернативная форма :
x={30°+k×180° ; 150+k×180° , k€z
x=30
