函数y=2sina^2 x+2cos x-3的最大值是?`````````请高手`写得详细些```````````

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函数y=2sina^2x+2cosx-3的最大值是?`````````请高手`写得详细些```````````函数y=2sina^2x+2cosx-3的最大值是?`````````请高手`写得详细些`

函数y=2sina^2 x+2cos x-3的最大值是?`````````请高手`写得详细些```````````
函数y=2sina^2 x+2cos x-3的最大值是?
`````````请高手`写得详细些```````````

函数y=2sina^2 x+2cos x-3的最大值是?`````````请高手`写得详细些```````````
y=2(sinx)^2+2cosx-3=2-(cosx)^2+2cosx-3
=-(cosx-1)^2
最大值0

y=2sina^2 x+2cos x-3
=2-2cos^2x+2cosx-3
=-2(cosx-1/2)^2-3/2
当cosx=1/2 时取到最大值-3/2