Collinear Points
Three or more points are collinear if they are part of the same straight line and as a result the rank of the vectors is 1.
Examples
1.Determine if the points A = (2, 3, 1), B = (5, 4, 3) and C = (2, 1, 2) are collinear.
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The points are not collinear.
Midpoint
If A = (x1, y1, z1) and B = (x2, y2, z2) are the endpoints of a line segment, the midpoint of the line segment is given by:
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Examples
1.Given the endpoints A = (3, −2, 5) and B = (3, 1, 7), find the coordinates of the midpoint of the line segment that they determine.
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2.The coordinates of consecutive vertices of a parallelogram are A = (1, 0, 0) and B = (0, 1, 0). If the center coordinates of M are (0, 0, 1), find the coordinates of the vertices C and D.

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