Question

How many planes contain the same three collinear points?

Answer 1

infinitely many

Explanation:

well if you think about it in a 3D plane

we can make to planes intercept at a line

and we can make another plane that another plane interceptes the other to planes in the same line

and another

and another

...

so we can have three points in the line (collinear) that the planes intercept and we are done

Answer 2

The points are collinear if the slope of any two pair of points is the same. Many infinite planes pass through that line. Thus, there are infinite planes contain the same three collinear plane.