t=a+x,x=t-a,dx=dt
∫arccos(a+x)dx
=arccostdt
=tarccost-Stdarccost
=tarccost+St/根号(1-t^2)dt
=tarccost-1/2*Sd(1-t^2)/根号(1-t^2)
=tarccost-根号(1-t^2)+c
=(x+a)arccos(x+a)-根号（1-(x+a)^2)+c
=(x+a)arccos(x+a)-根号(-x^2-2ax-a^2+1)+c
∫arccos(a+x)dx
t=a+x,x=t-a,dx=dt
∫arccos(a+x)dx
=arccostdt
=tarccost-Stdarccost
=tarccost+St/根号(1-t^2)dt
=tarccost-1/2*Sd(1-t^2)/根号(1-t^2)
=tarccost-根号(1-t^2)+c
=(x+a)arccos(x+a)-根号（1-(x+a)^2)+c
=(x+a)arccos(x+a)-根号(-x^2-2ax-a^2+1)+c