令x=2sint,则:dx=2costdt、√(4-x^2)=√[4-4(sint)^2]=2cost。∴∫{1/[x^2√(4-x^2)]}dx=∫{2cost/[(2sint)^2(2cost)]dt=(1/4)∫[1/(sint)^2]dt=-(1/4)cott+C=-(1/4)cost/sint+C=-(1/4)[2cost/(2sint)]+C=-√(4-x^2)/(4x)+C。
-0.25*cot(arcsin(x/2)) c