数学中,下面积分右边一结果是怎么来的?求个过程。
2个回答
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cos^2tdt/sin^2t=(1-sin^2t)dt/sin^2t=dt/(sin^2t)-dt
d(cost/sint)=dcost/sint+cost[dsin^(-1)t]=-sintdt/sint-cos^2t[sin^(-2)t]dt
=-sintdt/sint+cos^2tdt/(sin^2t)=(-sin^2t-cos^2t)dt/(sin^2t)=-dt/(sin^2t)
所以积分后为:-cost/sint-t代入[π/4,π/2]得-0-π/2-(-1-π/4)=1-π/4
d(cost/sint)=dcost/sint+cost[dsin^(-1)t]=-sintdt/sint-cos^2t[sin^(-2)t]dt
=-sintdt/sint+cos^2tdt/(sin^2t)=(-sin^2t-cos^2t)dt/(sin^2t)=-dt/(sin^2t)
所以积分后为:-cost/sint-t代入[π/4,π/2]得-0-π/2-(-1-π/4)=1-π/4
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