1. A line L passes through A(-1, 1). The mid-point of its intercept by the parallel lines L1: x + 2y – 1 = 0 and L2: x + 2y – 3 = 0 is B. B is also on the line L3: x – y – 1 = 0.
(a) Find the coordinates of the points C and D at which L1 and L2 cut the x-axis respectively.
一條關於Straight Lines的簡單A.Maths.Q
2009-03-08 3:38 am
回答 (1)
2009-03-08 7:26 am
✔ 最佳答案
1.(a)
L1: x + 2y - 1 = 0 ...... (1)
x-axis: y = 0 ...... (2)
Put (2) into (1):
x + 2(0) - 1 = 0
x = 1
Hence, the coordinate of C is (1, 0).
L2: x + 2y - 3 = 0 ...... (3)
x-axis: y = 0 ...... (2)
Put (2) into (3):
x + (0) - 3 = 0
x = 3
Hence, the coordinate of D is (3, 0).
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