正割三次方的不定积分详细过程

2024-11-21 23:32:33
推荐回答(2个)
回答1:

解:
∫[(secx)^3]dx
=(1/2)sinx(secx)^2+(1/2)∫secxdx
=(1/2)sinx(secx)^2+(1/2)ln|secx+tanx|

回答2:

∫(secx)^3 dx
=∫ dx/(cosx)^3
=∫d(sinx)/(cosx)^4, 令t=sinx
=∫dt*/(1-t^4)
=0.5∫dt*[1/(1-t^2)+1/(1+t^2)]
=0.5∫dt*[ 0.5/(1-t)+0.5/(1+t)+1/(1+t^2)]
=0.5[0.5ln|(1+t)/(1-t)|+arctant]+C
=1/4*ln|(1+sinx)/(1-sinx)|+1/2*arctan(sinx)+C