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Objective: Prove and use theorems about the angles formed by parallel lines and a transversal . Warm up: on handout. Who, When, Where, and Why Parallel?. Warm up. Creating Parallel line!. Now. First number each angle Next use your protractor to measure each angle you have created.
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Objective: Prove and use theorems about the angles formed by parallel lines and a transversal. Warm up: on handout Who, When, Where, and Why Parallel?
Now • First number each angle • Next use your protractor to measure each angle you have created. • Have you discovered anything?
Find each angle measure. A. mECF Corr. s Post. mECF = 70° B. mDCE 5x = 4x + 22 Corr. s Post. x = 22 Subtract 4x from both sides. mDCE = 5x = 5(22) Substitute 22 for x. = 110°
Find mQRS. x = 118 Corr. s Post. mQRS + x = 180° Def. of Linear Pair Subtract x from both sides. mQRS = 180° – x = 180° – 118° Substitute 118° for x. = 62°
Find each angle measure. A. mEDG mEDG = 75° Alt. Ext. s Thm. B. mBDG x – 30° = 75° Alt. Ext. s Thm. x = 105 Add 30 to both sides. mBDG = 105°
FYI (safety Vale) • The theorems we used today, were first established 2,300 years ago by this genius guy named Euclid. • Something that has stand the test of time has to be important, right? • Where are parallel lines used that make them important? You like cars? Etc..