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问题: 高中数学题求助,快~

若函数f(x)=(1+cos2x)/[2sin(π/2-x)]+sinx+a²sin(x+π/4)的最大值为3+√2,试确定常数a.

解答:

若函数f(x)=(1+cos2x)/[2sin(π/2-x)]+sinx+a²sin(x+π/4)的最大值为3+√2,试确定常数a.
解:f(x)=(1+cos2x)/[2sin(π/2-x)]+sinx+a²sin(x+π/4)
=2cos^x/[2cosx]+sinx+a²sin(x+π/4)
=cosx+sinx+a²sin(x+π/4)
=[cosx+sinx]+a²sin(x+π/4)
=√2[sinπ/4*cosx+sinxcosπ/4]+a²sin(x+π/4)
=√2[sin(x+π/4)]+a²sin(x+π/4)
=sin(x+π/4)]*(√2+a²)
最大值√2+a²=3+√2→a²=3∴a=±√3