Question

Найти:
cos(-780°)
Найти х
sin x=$\frac{ \sqrt{3} }{2}$

Answer 1

cos(-780)=cos780=cos(720+60)=cos60=1/2

sinx=√3/2
x=π/3+2πk U x=2π/3+2πk,k∈z

Answer 2

cos(-780°)=cos(-720°-60°)=cos(-60°)=cos(60°)=1/2.

sinx=√3/2
x=+-π/3+2πk, где k∈Z.