求不定积分:∫sinxcosx⼀(cosx+sinx) dx 急!!谢谢各位大侠,不用万能代换...

2024-11-19 04:23:47
推荐回答(3个)
回答1:

见图

回答2:

∫sinxcosx/(cosx+sinx) dx
=∫sinxcosx(cosx-sinx) /[(cosx+sinx) (cosx-sinx) ]dx
=∫sin2x(cosx-sinx) /cos2x]dx
=∫tan2x(cosx-sinx) dx
看看这样能做不?

回答3:

∫sinxcosx/(cosx+sinx) dx =-(1/4)∫d(1-2sin^2x)/(1-2sin^2x) = -(1/4)ln(1-2sin^2x)+C