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There are eight angles, but only two angle measurements. All of the acute angles are congruent. 1 = 4 = 5 = 8 All of the obtuse angles are congruent. 2 = 3 = 6 = 7 The two different angle measurements are supplementary (their sum is 180°) ~ ~ ~ ~ ~ ~ Congruent Corresponding Alternate Interior Alternate Exterior There are five special terms that describe angle relationships in the figure above. Three refer to congruent angle pairs. Two refer to supplementary angle pairs. Supplementary Same Side Interior Same Side Exterior Corresponding angles are congruent. The corresponding pairs of angles are: 1 = 5 2 = 6 3 = 7 4 = 8 ~ ~ ~ ~ Alternate means on the other side of the transversal. Interior means between the parallel lines. Alternate interior angles are congruent. The alternate interior pairs of angles are: 3 = 6 4 = 5 ~ ~ Alternate means on the other side of the transversal. Exterior means outside of the parallel lines. Alternate exterior angles are congruent. The alternate exterior pairs of angles are: 1 = 8 2 = 7 ~ ~ Same side means on the same side of the transversal. Interior means between the parallel lines. Same side interior angles are supplementary. The same side interior pairs of angles are: angle 3 + angle 5 = 180 angle 4 + angle 6 = 180 Same side means on the same side of the transversal. Exterior means between the parallel lines. Same side exterior angles are supplementary. The same side exterior pairs of angles are: angle 1 + angle 7 = 180 angle 2 + angle 8 = 180 GET READY FOR A QUICK QUIZ! Terms: Corresponding Alternate Interior Alternate Exterior Same Side Interior Same Side Exterior 1. Which angle is alternate interior to angle 3? angle 6 angle 4 angle 2 angle 5 2. Which angle is alternate exterior to angle 7? angle 1 angle 2 angle 3 angle 8 3. Which angle corresponds to angle 2? angle 1 angle 3 angle 6 angle 7 4. Which angle is same side interior to angle 4? angle 6 angle 1 angle 3 angle 5 5. Which angle is same side exterior to angle 2? angle 1 angle 4 angle 7 angle 8 |