5.1 Properties of Parallelograms
Obj: List the properties of parallelograms
Parallelograms: • Opposite sides are parallel. • Opposite sides are congruent. • Opposite angles are congruent. • Diagonals bisect each other. (c) 2007 brainybetty.com ALL RIGHTS RESERVED.
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Think… • What can we say about the consecutive angles of parallelograms? • Supplements (same side interiors)
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Example 1 • ABCD is a parallelogram. Find the values of x, y and z. D
A)
C y
z
65° A
x B (c) 2007 brainybetty.com ALL RIGHTS RESERVED.
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B)
56
y
z
85
x
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C) 28
25
3x + 4
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2y - 8
6
2x + y
D) 4x - y
24
36 (c) 2007 brainybetty.com ALL RIGHTS RESERVED.
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Example 2 • The perimeter of pgram HIJK is 72 cm. Find HI and IJ if HI is 4 cm shorter than IJ.
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Example 3 • Determine if the following quadrilaterals are parallelograms and state why. 1
• A) 3
2
4 ∠1 ≅ ∠4 ∠2 ≅ ∠3
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• B) 6
5
∠5 ≅ ∠6 (c) 2007 brainybetty.com ALL RIGHTS RESERVED.
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• C)
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• D)
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Homework: • Page 169; 5-12, 22, 24
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Homework • Worksheet 5-2
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