alternate angle

alternate angleAngles 3 and 6 are alternate interior angles, as are angles 4 and 5. Angles 1 and 8 are alternate exterior angles, as are angles 2 and 7.

al·ter·nate angle

(ôl′tər-nĭt, ăl′-)n. One of a pair of nonadjacent angles on opposite sides of a transversal that cuts two lines. The angles are both exterior or both interior to the two lines.

al′ternate an′gle

n. one of a pair of nonadjacent angles made by the crossing of two lines by a third line.