x趨向於π,(1+cosX)/(x-π)^2,求極限.

x趨向於π,(1+cosX)/(x-π)^2,求極限.

limx趨向於π,(1+cosX)/(x-π)^2
令x-π=t
x=π+t
原式=lim(t->0)(1+cos(π+t))/t^2
=lim(t->0)(1-cost)/t^2
=lim(t->0)(t²;/2)/t^2
=1/2