Given a point on the plane, one can draw _______ lines through that point.

Let and be two parallel lines and be a transversal. Show that the angle bisectors of a pair of two internal angles on the same side of the transversal are perpendicular to each other.

If a = 60 and b = a, then b = 60 by _________

Given two points in a plane, the number of lines which can be drawn to pass through these two points is _________

If two angles are supplementary, then their sum is _______