f(x)＝√3cos（π/2-2x）＋2cos^2x＋2
=√3sin2x＋(1+cos2x)＋2
=√3sin2x＋cos2x+3
=2(√3/2sin2x＋1/2cos2x)+3
=2sin(2x+π/6)+3
T=2π/2=π
2)asinB＝3bcosA
sinAsinB=√3sinBcosA
tanA=√3
A=π/3
b＝f（-π/3）,
b=f（-π/3）=2sin(-2x/3+π/6)+3=-2sinπ/2+3=-2+3=1
S=1/2bcsinπ/3=√3
c=4
a^2=b^2+c^2-bc=1+16-4=13
a=√13