Detailed description
Parallel lines AB and CD crossed by a transversal EF. Pairs of vertically opposite angles are labelled alpha and beta at each of the points of intersection. The sum of alpha and beta is 180 degrees.
Angles and parallel lines
Parallel lines AB and CD crossed by a transversal EF. Pairs of vertically opposite angles are labelled alpha and beta at each of the points of intersection. The sum of alpha and beta is 180 degrees.