Question

2cos в квадрате x-5cosx+2=0

Answer 1

Cosx=y
2y^2-5y+2=0
(2y-1)(y-2)=0
y=1/2
y=2
y=2 не берем т.к cos и sin [-1;1]
cosx=1/2
X=p/3+2pk k€Z