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3.4 – Proving Lines Parallel. Reasons:. Corresponding Angles Converse – If two lines are cut by a transversal so that the corresponding angles are congruent, then the two lines are parallel
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Reasons: • Corresponding Angles Converse – If two lines are cut by a transversal so that the corresponding angles are congruent, then the two lines are parallel • Consecutive Interior Angles Converse – If two lines are cut by a transversal so that the consecutive interior angles are supplementary, then the two lines are parallel
More Reasons • Alternate Interior Angles Converse – If two lines are cut by a transversal so that the alternate interior angles are congruent, then the two lines are parallel • Alternate Exterior Angles Converse – If two lines are cut by a transversal so that the alternate exterior angles are congruent, then the two lines are parallel • (use converses when proving parallel lines)
<5 <6, <6 <4 <5 <4 AD | | BC Given Transitive Alternate Interior Angles Converse Given: <5 <6, <6 <4Prove AD | | BC
<1 and <5 are suppl. <4 and < 1 are suppl. <5 <4 j | | k Given Congruent Supplements Theorem Alternate Interior Angles Converse Given: <1 and <5 are supplements, <1 and <4 are supplementsProve: j | | k
Example • What theorem could you use to prove the lines are parallel? Alternate Interior Angles Converse
Assignment • P. 153-154 10-18, 20-28all