Angle Relationships and Parallel Lines Flashcards

Grade 8 · Math · Flashcards

Master all key angle pairs for intersecting lines and parallel lines cut by a transversal.

Flashcards

Vertical angles: Opposite angles at an intersection; always congruent (equal).
Supplementary angles: Two angles summing to 180 degrees; they form a straight line.
Complementary angles: Two angles summing to 90 degrees; they form a right angle.
Adjacent angles: Angles sharing a vertex and a side but not overlapping.
Transversal: A line crossing two or more parallel lines, creating special angle pairs.
Corresponding angles: Same position at each intersection of parallel lines; congruent.
Alternate interior angles: Opposite sides of transversal, between parallel lines; congruent.
Alternate exterior angles: Opposite sides of transversal, outside parallel lines; congruent.
Co-interior angles: Same side of transversal, between parallel lines; supplementary (sum = 180).
Test for parallel lines: If alternate interior angles are equal, the lines are parallel.
Angles on a straight line: All angles on one side of a straight line sum to 180 degrees.
Angles around a point: All angles around a single point sum to 360 degrees.