suppose that four lines in a given plane a1, a2, b1, b2 are given, with the conditions (also given) that, a1 II a2, b1 II b2, and a1 is neither parallel nor perpendicular to b1.

In any diagram that illustrates the given conditions, how many distinct angles are formed? Count only angles that measure less than 180 degrees and count two angles as the same only if they have the same vertex and same edges. Among these angles, how many different angle measures are formed? Justify your answer.