Many origami models begin with a square piece of paper,
�
JKLM, that is folded along both diagonals to make the
̶̶
̶̶̶ creases shown. JL and MK are perpendicular bisectors of each other, and ∠NML ≅ ∠NKL.
̶̶
̶̶̶
�
a. Explain how you know that KL and ML are congruent.
�
b. Prove △NML ≅ △NKL.
�
�
27. Draw a diagram and then write a proof.
̶̶ ̶̶ ̶̶
̶̶ ̶̶
̶̶
Given: BD ⊥ AC. D is the midpoint of AC. AB ≅ CB, and BD bisects ∠ABC.
Prove: △ABD ≅ △CBD
28. Critical Thinking Draw two triangles that are not congruent but have an area of
4 cm 2 each.
29.
�
/////ERROR ANALYSIS/////
Given △MPQ ≅ △EDF.
Two solutions for finding m∠E are shown.
Which is incorrect? Explain the error.
���
�
�
�
�
�
�
�
�������������������������
�������������������������
����������
���������������������������
������������������������
����������������������
30. Write About It Given the diagram of the triangles, is there enough information to prove that △HKL is congruent to △YWX? Explain.
�
�
31. Which congruence statement correctly indicates that the two given triangles are congruent?
△ABC ≅ △EFD
△ABC ≅ △DEF
△ABC ≅ △FDE
△ABC ≅ △FED
�
� �
�
�
�
�
�
�
�
32. △MNP ≅ △RST. What are the values of x and y?
1
2 x = 26, y = 21_ x = 25, y = 20_
3
3
1
2
_
x = 27, y = 20 x = 30 , y = 16_
�
3
3
�
���
��� ���
�
���������
�
��������������
�
�
���������
33. △ABC ≅ △XYZ. m∠A = 47.1°, and m∠C = 13.8°. Find m∠Y.
13.8
76.2
42.9
119.1
34. △MNR ≅ △SPQ, NL = 18, SP = 33, SR = 10, RQ = 24, and QP = 30. What is the perimeter of △MNR?
79
87
85
97
236
Chapter 4 Triangle Congruence
�
�
�
�
�
�
�