Through any given set of four distinct points P, Q, R and S, it is possible to draw at most ___circle(s).
At most one circle can be drawn through a given set of four distinct points. These points are called concyclic points.
Through any given set of four distinct non-collinear points P, Q, R, S it is possible to draw at most ___circle(s).
Through any given set of three distinct points A, B, C it is possible to draw at most ___circle(s).
Let l be a line and P be a point not on l. Through P, draw a line m parallel to l. Now join P to any point Q on l. Choose any other point R on m. Through R, draw a line parallel to PQ. Let this meet l at S. What shape do the two sets of parallel lines enclose?