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直线y=-1/ 2 x-1与x轴交于点A,与y轴交于点B,将此直线向上平移4个单位后与双曲线y=k x (x>0)交于C

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直线y=-1/ 2 x-1与x轴交于点A,与y轴交于点B,将此直线向上平移4个单位后与双曲线y=k x (x>0)交于C、D
cd=2ab    求详解
直线y=-1/ 2 x-1与x轴交于点A,与y轴交于点B,将此直线向上平移4个单位后与双曲线y=k x (x>0)交于C
y = -x/2 - 1,A(-2,0),B(0,-1),AB = √5
向上平移4个单位后,变为y = -x/2 - 1 + 4 = -x/2 + 3
C(c,3- c/2),D(d,3 - d/2)
c(3 - c/2) = d(3 - d/2) = k
3(c - d) = (1/2)(c + d)(c - d)
c ≠ d,c + d = 6,d = 6 - c
D(6 - c,c/2)
CD² = (c - 6 + c)² + (3 - c/2 - c/2)² = 5(c - 3)² = (2AB)² = 20
(c - 3)² = 4
c = 1,d = 5 (按图,舍去c = 5,d = 1)
C(1,5/2)
双曲线y= (5/2)/x = 5/(2x)