Q:

In the given the figure above, m∠BAC = 64° and m∠CBA = 56°. Part I: Find the m∠DEC. Part II: Explain the steps you took to arrive at your answer. Make sure to justify your answer by identifying any theorems, postulates, or definitions used.

Accepted Solution

A:
Answer:56, see step-by-step. Step-by-step explanation:1. AB is parallel to CD.                                1. Given   BC is parallel to DE.   m<BAC=64 and m<CBA =562. m<BAC + m<CBA + m<BCA =180       2. The angles in a triangle add up to       1803. 64+ 56+ m<BCA=180 3. Substitution property of equality. 4. 120 + m<BCA=180 4. Addition property of equality. 5. m<BCA=60 5. Subtraction property of equality. 6. BC is a transversal that cuts through parallel lines AB and CD. 6. Def. of transversal. 7. m<CBA = m<BCD 7. If two parallel lines are cut by a transversal, then alternate interior angles are congruent. 8. m<BCA+m>BCD+m<DCE= 180. 8. Angle addition postulate9. 60+56+m<DCE=180. 9.substitution.10. 116 + m<DCE =180 10. Addition property of equality.11. M<DCE =64 11. Subtraction property of equality. 12. DC is a transversal that cuts through parallel line BC and DE. 12. Def of transversal. 13. m<EDC= m<BCD 13. If two parallel lines are cut by a transversal, then alternate interior angles are congruent. 14. m<EDC= 60. 14. Substitution property of equality.15. m<EDC+m<DCE+m<Dec=180. 15. Angle addition postulate16. 56+64+m<dec = 180.16 Substitution property of equality. 17. 120+ m<dec = 180. Addition property of equality. 18. m<dec = 60 18. Subtraction property of equality.