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Horizontal Line Test Area of a Hexagon Area of a Triangle 1 Piecewise Functions Perimeter of Shapes Prime Numbers Permutations without RepetitionCollinear points are points that lie in a straight line.
In particular, 3 or more points are collinear if:
- they lie in a straight line,
AND
- share a common point.
Show that the points
A(2,1), B(4,3)  and C(6,5) are Collinear.
Technically you could draw the points and a line on a suitable axis to observe Collinearity.
But this is not really the best Mathematical way to establish collinearity in such a
situation.
We really want to try to work out the gradient/slope between the points.
As points that are in a straight line with each other, will produce the same value for the gradient.
Because they are all lined up in the same slope/direction.
If the gradient from point A to point B, and point B to point C
are the same.
Then those points will be collinear, as point B will be a shared common point.
Both line segments AB and BC, have the same slope in the same direction, and share
a common point in B.
So all  3 points are indeed Collinear.
Unless they are parallel, and sloping in the exact same direction, like in the diagram below.
Two straight lines will have a point of intersection, which is a point where they cross over or touch
each other.
To work out a specific point of intersection between  2 straight lines. We first want to
know the equations of both lines.
Then set the equations equal to each other. As at the point of intersection, both lines will have
the same x and y values.
Then once an x value is obtained, this can be
substituted into one of the original straight line equations, to give the y co-ordinate of the point of intersection.
At what point do the following straight lines intersect.
First set the equations equal to each other.