Question

如图,P是定长线段AB上一点,C、D两点分别从P、B出发以1cm/s、2 cm/s的速度沿直线AB向左运动

Answer 1

AB=30cm,当C,D运动时间为1S时,

PC = 1*1 = 1

BD = 2*1 = 2

AC = AP-PC = AP-1

PD = PB-BD = PB-AP-BD = 30-AP-2 = 28-AP

PD = 2AC

28-AP = 2(AP-1)

3AP = 30

AP = 10

AB=30cm,当C,D运动时间为1S时,

PC = 1*2 = 2

BD = 2*2 = 4

AC = AP-PC = AP-2

PD = PB-BD = PB-AP-BD = 30-AP-4 = 26-AP

PD = 2AC

26-AP = 2(AP-2)

3AP = 30

AP = 10 cm

AB=30cm,当C,D运动时间为1S时,

PC = 1*1 = 1

BD = 2*1 = 2

AC = AP-PC = AP-1

PD = PB-BD = PB-AP-BD = 30-AP-2 = 28-AP

PD = 2AC

28-AP = 2(AP-1)

3AP = 30

AP = 10

AB=30cm,当C,D运动时间为任意时间t时,

PC = 1*t = t

BD = 2*t = 2t

AC = AP-PC = AP-t

PD = PB-BD = PB-AP-BD = 30-AP-2t

PD = 2AC

30-AP-2t = 2(AP-t)

3AP = 30

AP = 10 cm