Corresponding angles occur when two lines are crossed by the same line (a transversal).[br]The corresponding angles are the same colour.

Drag the points A and B to change the angles. [br]The blue and red lines are always parallel so the corresponding angles are [b]always[/b] equal.[br][br]Drag the points K and I. The corresponding angles are [b]only[/b] equal when the blue and red lines are parallel.