arctan(1/x^2)求x趋近于0的极限怎么求?

题目

arctan(1/x^2)求x趋近于0的极限怎么求?

答案

答：
设1/x^2=t
lim(x→0) arctan(1/x^2)
=lim(t→+∞) arctan(t)
=π/2