A(1,5)B(4,1)C(2,-1) mx-y-2m+6=0与△ABC恒有公共点,实数m的取值范围是
问题描述:
A(1,5)B(4,1)C(2,-1) mx-y-2m+6=0与△ABC恒有公共点,实数m的取值范围是
答
依题设,得 直线mx-y-2m+6=(x-2)m+(6-y)=0过定点M(2,6),斜率为m,且MC⊥x轴,则
m≥kMA=1或m≤kMB=-5/2