cos(x)≡1-2sin2(x/2) (trig identity), now substitute for cos(x):
2sin2(x/2)+3(1-2sin2(x/2))=2,
2sin2(x/2)+3-6sin2(x/2)=2,
1=4sin2(x/2),
sin2(x/2)=¼,
sin(x/2)=±½.
x/2=π/6, 5π/6, 7π/6, 11π/6, ...
In general, x/2=π/6+2nπ, 5π/6+2nπ, where n is an integer.
x=π/3+4nπ, 5π/3+4nπ.