(cosx)^2=1/2*(1+cos2x)
3^0.5*sinxcosx=1/2*3^0.5*sin2x
y=1/2+1/2*cos2x+3^0.5 /2 *sin2x
y=1/2+sinπ/6*cos2x+cosπ/6*sin2x
y=1/2+sin(π/6+2x)
區(qū)間[-π/6,π/4]
則2x+π/6∈[-π/6,2π/3]
其中[-π/6,0]為負(fù),增函數(shù)
[0,π/2]為正,增函數(shù)
[π/2,2π/3],為正減函數(shù)
其中最大值為π/2點,最小值為-π/6點
y∈[1/2+sin(-π/6),1/2+sinπ/2]
即[0,3/2]