Question

if four points are collinear, are they also coplanar? explain.

Answer 1

does one line have to lie in a plane? can a line be beyond one plane and contained in two?
think of the normal to a plane.

Answer 2

@chitthuzin98

>>if four points are collinear, are they also coplanar?
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To say that four points are collinear is to say that there is a line that contains all four points.

There exists at least one plane which will contain the line. That means that the points on the line are also coplanar.