y =( 1+cos2x)* 1+ 1 *(ì3s in2x+a)+ 1

=√3sin2x+cos2x+a+ 1

=2sin(2x+π/6)+a+ 1

2)

0≤x≤π/2 = = & gt； π/6≤2x+π/6≤7π/6

When 2x+π/6=π/2; That is, when x=π/6, y takes the maximum value, and y(MAX)=3+a=4.

a= 1

3)

y=2sin(2x+π/6)+ 1

y = sinx-& gt； (left shift π/6 units)-> y = sin(x+π/6)-& gt； (the abscissa is reduced to half of the original)-> y = sin(2x+π/6)-& gt；

-& gt； (The vertical axis is twice the original)-> y = 2sin(2x+π/6)-& gt； (the ordinate moves up 1 unit)-> y=2sin(2x+π/6)+ 1