3-2 angles formed by parallel lines and...
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3-14 Holt Geometry
Reteach Angles Formed by Parallel Lines and Transversals
According to the Corresponding Angles Postulate, if two parallel lines are cut by a transversal, then the pairs of corresponding angles are congruent.
Determine whether each pair of angles is congruent according to the Corresponding Angles Postulate.
1. ∠1 and ∠2 2. ∠3 and ∠4
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Find each angle measure.
3. m∠1 4. m∠HJK
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5. m∠ABC 6. m∠MPQ
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LESSON
3-2
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3-15 Holt Geometry
Reteach Angles Formed by Parallel Lines and Transversals continued
If two parallel lines are cut by a transversal, then the following pairs of angles are also congruent. If two parallel lines are cut by a transversal, then the pairs of same-side interior angles are supplementary.
Find each angle measure.
7. m∠3 8. m∠4
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9. m∠RST 10. m∠MNP
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11. m∠WXZ 12. m∠ABC
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LESSON
3-2
Angle Pairs Hypothesis Conclusion
alternate interior angles
∠2 ≅ ∠3 ∠6 ≅ ∠7
alternate exterior angles
∠1 ≅ ∠4 ∠5 ≅ ∠8
m∠5 + m∠6 = 180° m∠1 + m∠2 = 180°
Original content Copyright © by Holt McDougal. Additions and changes to the original content are the responsibility of the instructor.
A22 Holt Geometry
9. m∠2 = m∠ABE + m∠CBE 9. Angle Add. Post.
10. m∠1 + m∠2 + m∠3 + m∠4 = 360°
10. Subst. (Steps 8, 9)
Reteach 1. no 2. yes 3. 67° 4. 142° 5. 92° 6. 125° 7. 111° 8. 90° 9. 138° 10. 56° 11. 130° 12. 118°
Challenge 1. Justifications may vary. All lines directed
due north are parallel. A heading that is read off the compass is the same as the ship’s heading.
2. about 102° 3. about 38° 4. about 170° 5. about 256°
Problem Solving 1. 17; Alt. Int. s∠ Thm. 2. 102°; Alt. Ext. s∠ Thm. 3. x = 10; y = 3; (12x + 2y)° = 126° by the Corr.
s∠ Post. and (3x + 2y)° = 36° by the Alt. Int. s∠ Thm.
4. D 5. H
Reading Strategies 1. ∠1 ≅ ∠5 2. ∠2 ≅ ∠6 3. ∠3 ≅ ∠7 4. ∠4 ≅ ∠8 5. ∠2 ≅ ∠8 6. ∠3 ≅ ∠5 7. ∠1 ≅ ∠7 8. ∠4 ≅ ∠6 9. m∠2 + m∠5 = 180° 10. m∠3 + m∠8 = 180° 11. m∠6 = 47° by the Corresponding Angles
Postulate 12. m∠3 = 133° by the Same-Side Interior
Angles Theorem
LESSON 3-3
Practice A 1. parallel
2. Conv. of Corr. s∠ Post. 3. m∠7 = 68°, ∠3 ≅ ∠7, Conv. of Corr. s∠
Post. 4. transversal; congruent 5. supplementary 6. parallel 7.
Statements Reasons
1. ∠1 and ∠3 are supplementary.
1. a. Given
2. b. ∠2 and ∠3 are supplementary. 2. Linear Pair Thm.
3. ∠1 ≅ ∠2 3. c. ≅ Supps. Thm.
4. d. m || n 4. Conv. of Corr. s∠ Post.
Practice B 1. m || n; Conv. of Alt. Int. s∠ Thm. 2. m || n; Conv. of Corr. s∠ Post. 3. m and n are parallel if and only if
m∠7 = 90°. 4. m || n; Conv. of Same-Side Int. s∠ Thm. 5. m and n are not parallel. 6. m || n; Conv. of Corr. s∠ Post. 7. m || n; Conv. of Alt. Ext. s∠ Thm. 8. m and n are not parallel. 9. Sample answer: The given information
states that ∠1 and ∠3 are supplementary. ∠1 and ∠2 are also supplementary by the Linear Pair Theorem. Therefore ∠3 and ∠2 must be congruent by the Congruent Supplements Theorem. Since ∠3 and ∠2 are congruent, HI and JK are parallel by the Converse of the Corresponding Angles Postulate.
Practice C 1. x = 11; y = −5; m∠1 = 57°; m∠2 = 57°;
m∠3 = 123°
2.