f(a) = 根号（3）sina = 3根号（3）/5
sin a= 3/5
cos a= 4/5
2 sin^)2 a/2 = 1-cosa = 1/5
f(x) > g(x)
2sin(x+pi/6)>1
sin(x+pi/6) > 1/2
2npi + 5pi/6 > x+pi/6 > 2npi + pi/6
2npi < x < 2npi + 2pi/3