The Cartesian plane
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Distance between two points
Distances are always positive. If 2 points coincide, the distance between them is zero. The distance from A to B is the same as the distance from B to A. We first find the distance between 2 points that are either vertically or horizontally aligned.
EXAMPLE
Find the distance between the following pairs of points.
a
A(1, 2) and B(4, 2)b A(1, −2) and B(1, 3)
Solution
a The distance AB = 4 − 1 = 3
Note: The distance AB is obtained from
the difference of the x-coordinates of
the 2 points.
b The distance AB = 3 − (−2) = 5
Note: The distance AB is obtained from
the difference of the y-coordinates of the
2 points.
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