y=sinxcosx+（cosx）^2
=1/2*sin2x+1/2*(1+cos2x)
=1/2sin2x+1/2cos2x+1/2
=√2/2(√2/2sin2x+√2/2cos2x)+1/2
=√2/2sin(2x+π/4)
当2x+π/4=2kπ+π/2,k∈Z
即x=kπ+π/8,k∈Z时,
ymax=√2/2+1/2
当2x+π/4=2kπ-π/2,k∈Z
即x=kπ-3π/8,k∈Z时,
ymin=-√2/2+1/2
y=4+4sinx-(cosx)^2
=4+4sinx-(1-sin²x)
=sin²x+4sinx+3
=(sinx+2)²-1
∵-1≤sinx≤1
∴当sinx=-1,即x==2kπ-π/2,k∈Z
ymin=0
当sinx=1,即x=2kπ+π/2,k∈Z
ymax=8