求lim(0~正无穷)∫(0~∞)(arctanx)^2/(X^2+1)^1/2dx

求lim(0~正无穷)∫(0~∞)(arctanx)^2/(X^2+1)^1/2dx
求lim(0~正无穷)∫(0~∞)(arctanx)^2/(X^2+1)^1/2dx

求lim(0~正无穷)∫(0~∞)(arctanx)^2/(X^2+1)^1/2dx
罗比达法则,一直化简到2arctanx/（1/根号1+x^2)就可~
中间一部为2arctanx/（根号1+x^2-x^2/根号1+x^2)就可