华中师范大学专用
(12)
1
sinxcos4dx
=
xsin2x+cos2xdx
=
sinxcos4xsinx
1 +dxsinx
sin2x+cos2=dx+xdx
= dcosx sinx1
cosx+[cosx+sinx
]dx
=
1
3cos3x+1cosx+ln|tanx2
|+C.(12)
1
sindx
==u=cos====x
==
xcosx 1(1 u2)udu
=
4
1
11 u2 1 u2 u4dx=11 u112ln1+u+u+3u
=112ln
1 cosx1+cosx+3cos3x+1cosx
+C.16
(0.41)
(0.42)