求极限:lim(1-x)tan Π/2

问题描述:

求极限:lim(1-x)tan Π/2

tan(πx/2)吧? lim(x→1) (1-x)tan(πx/2)=lim(x→1) (1-x) sin(πx/2)/cos(πx/2)=lim(x→1) (1-x) /cos(πx/2)=lim(x→1) (1-x) /sin(π/2-πx/2)=lim(x→1) (1-x) /(π/2-πx/2)=2/π希望采纳...