Given: and bisect each other. Prove: Quadrilateral ABCD is a parallelogram. Proof: Statement Reason 1. and bisect each other. gi
ven 2. AE = EC BE = ED definition of bisection 3. m∠AEB = m∠CED 4. ΔABE ≅ ΔCDE SAS criterion 5. ∠ACD ≅ ∠CAB Corresponding angles of congruent triangles are congruent. 6. converse of Alternate Interior Angles Theorem 7. m∠BEC = m∠AED Vertical Angles Theorem 8. ΔBEC ΔDEA SAS criterion for congruence 9. DBC ≅ BDA Corresponding angles of congruent triangles are congruent. 10. converse of Alternate Interior Angles Theorem 11. Quadrilateral ABCD is a parallelogram. definition of a parallelogram 1 What is the reason for step 3 of this proof? A. Alternate Interior Angles Theorem B. Corresponding angles in congruent triangles are congruent. C. For parallel lines cut by a transversal, corresponding angles are congruent. D. Vertical Angles Theorem E.
2 answers:
Answer:
To Prove: Quadrilateral ABCD is a parallelogram.
Proof: In Δ ABE and ΔCDE
1. AE = EC and BE = ED [ Diagonals bisect each other]
2.∠ AEB = ∠ CED [ vertically opposite angles]
Δ ABE ≅ ΔCDE---------- [SAS]
∠ ACD ≅ ∠CAB [Corresponding angles of congruent triangles are congruent⇒This statement is untrue ∴ these are alternate interior angles not corresponding angles.]
6. The converse of alternate interior interior angle theorem states that if two parallel lines are cut by a transversal then alternate interior angles are equal.
7. In ΔBEC and ΔAED
∠BEC = ∠AED [ Vertical Angles Theorem ]
AE = EC and BE = ED [ Diagonals bisect each other]
⇒ ΔBEC≅ ΔDEA [ SAS criterion for congruence]
9. DBC ≅ BDA [ Corresponding angles of congruent triangles are congruent⇒This statement is untrue ∴ these are alternate interior angles not corresponding angles.]
As pair of triangles are congruent ∵ quadrilateral ABCD is a parallelogram.
Step 3 is m∠AEB = m∠CED
These pair of angles are vertically opposite angles of ΔAEB and ΔCED.
Option [D. Vertical Angles Theorem] is correct.
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Answer:
m∠SRV = 48°
Step-by-step explanation:
In the parallelogram attached,
m∠TUV = 78°
m∠TVU = 54°
By applying the property of the angles of a triangle in ΔTVU,
m∠TUV + m∠TVU + m∠UTV = 180°
78° + 54° + m∠UTV = 180°
m∠UTV = 180° - 132°
= 48°
Sides RS and TU are the parallel sides of the parallelogram and diagonal TR is a transverse.
Therefore, ∠UTV ≅ ∠SRV [Alternate interior angles]
m∠UTV = m∠SRV = 48°
