解:
设x=asint,t=arcsin(x/a),a^2-x^2=a^2(cost)^2,dx=acostdt
原式=∫7a^2(sint)^2/a^2(cost)^2dt
=∫7(tant)^2dt
=7∫((sect)^2-1)dt
=7∫(sect)^2dt-7∫dt
=7tant-7t
=7(x/a)/根号(1-(x/a)^2) -7arcsin(x/a)
设x=asinu,dx=acosudu
原式=∫7a²sin²u/(a³cos³u)*acosudu
=7∫tan²udu
=7∫(sec²u-1)du
=7(tanu-u)+C
=7[x/√(a²-x²)-arcsin(x/a)]+C
我操 神人辈出啊