定积分I=∫(π/4到5π/4) [1+(sinx)^2]dx的取值范围

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定积分I=∫(π/4到5π/4) [1+(sinx)^2]dx的取值范围
定积分I=∫(π/4到5π/4) [1+(sinx)^2]dx的取值范围

定积分I=∫(π/4到5π/4) [1+(sinx)^2]dx的取值范围
是求I的取值范围,不是求定积分
4个选项(

I=∫[π/4,5π/4][1+(1-cos2x)/2]dx
=∫[π/4,5π/4][3/2-(cos2x)/2]dx
=(3x/2)[π/4,5π/4]-sin(2x)/4[π/4,5π/4]
=(3/2)(5π/4-π/4)-(1/4)(sin5π/2-sinπ/2)
=3π/2-(1/4)(1-1)
=3π/2.是求I的取值范围,不是求定积分 4个...

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I=∫[π/4,5π/4][1+(1-cos2x)/2]dx
=∫[π/4,5π/4][3/2-(cos2x)/2]dx
=(3x/2)[π/4,5π/4]-sin(2x)/4[π/4,5π/4]
=(3/2)(5π/4-π/4)-(1/4)(sin5π/2-sinπ/2)
=3π/2-(1/4)(1-1)
=3π/2.

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