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3-2 Angles Formed by Parallel Lines and Transversals Objective Holt Geometry 10/29 Lesson 3.2 2 1 What is the name of the angle pair, angles 1 and 2? 3-2 Angles Formed by Parallel Lines and Transversals What if the lines are parallel? 2 1 Holt Geometry 3-2 Angles Formed by Parallel Lines and Transversals Postulate or Theorem Name What it says Key Words If 2 parallel lines are cut by a transversal, then… Corresponding …the corresponding Angles angles are congruent. Postulate Holt Geometry Parallel lines Transversal Corresponding angles Picture 3-2 Angles Formed by Parallel Lines and Transversals Find mQRS. Holt Geometry 3-2 Angles Formed by Parallel Lines and Transversals Example 1) 4 m 8 7 n 5 3 1 2 6 If m<8 = 61˚, find the measures of all other numbered angles. Holt Geometry 3-2 Angles Formed by Parallel Lines and Transversals Example 2) 4 m 8 7 n 5 3 1 2 6 Alternate Interior angles are ____________. Alternate exterior angles are ____________. Same-side interior angles are ____________. Holt Geometry 3-2 Angles Formed by Parallel Lines and Transversals Alternate …the alternate interior Interior Angles angles are congruent. Theorem Parallel lines Transversal Alternate interior angles Alternate …the alternate exterior Exterior Angles angles are congruent. Theorem Parallel lines Transversal Alternate exterior angles Same-side Interior Angles Theorem Holt Geometry Parallel lines Transversal …the same-side interior Same-side interior angles are supplementary. angles Supplementary 3-2 Angles Formed by Parallel Lines and Transversals Find each angle measure. A. mDCE B. mCBG Holt Geometry 3-2 Angles Formed by Parallel Lines and Transversals Example 3) Given m3 = 3x-1 and m5 = x+5. Find m1. Holt Geometry 3-2 Angles Formed by Parallel Lines and Transversals Example 4) Given m3 = 2(x-35) and m4 = x+15. Find m5. Holt Geometry 3-2 Angles Formed by Parallel Lines and Transversals Objective Holt Geometry Exit Slip! 1. Let m1 = 120°, m2 = (60x)° . a. Give the name of the angle pair that describes <1 and <2. b. Write and solve an equation to find the measures of the angles. c. Name the theorem or postulate that justifies your solution. 2. Find m3 and m5 if m3 = (45x + 30)° and m5 = (25x + 10)° .