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Geometry Guided Notes – Lesson 6.5 Name __________________________________
Definition – The ______________ sides of a trapezoid are its bases. The _________________ sides are its legs.
Two angles that share a _________ of a trapezoid are base angles of the trapezoid.
Theorem 6-15: The base angles of an isosceles trapezoid are ___________________.
* Copy this onto your quadrilateral chart *
The bases of a trapezoid are ______________. Therefore the two angles that share a leg are _____________________________.
Examples: Find the values of the missing angles.
1. 2. 3.
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1 ________

2 _______

1 _______

2 _______

1 ________
4. The spiders web to the right is formed by a layer of congruent isosceles triangles followed
by layers of congruent isosceles trapezoids.
Find the measures of the angles in ABDC.
Hint: To begin, remember the angles of a circle add up to 360°. Decimal answers are OK!

2 _______
 DAB
_________
 ABC
________
 BCD
___________
 CDA
___________
Examples: Find the values of the variables in the following figures.
5.
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6.
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7.
Theorem 6-16: The ________________ of an isosceles trapezoid are ______________________.
* Copy this onto your quadrilateral chart *
Example : Find the value of x and find AC and BD .
AC = 10 x – 60
BD = 2 x + 100

1.
Theorem 6-17: The ________________ of a kite are __________________________.
* Copy this onto your quadrilateral chart *
Examples: Find the values of the missing angles.
2.

1 ________

2 _______

1 ________

2 _______
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3.
1 _______

2 _______

3 ______
Examples : Find the values of the variables in the following figures.
4. 5.
Homework 6.5
: p.338 #2-6even, 8-12 even, 20, 22, 24, 26, 27
6.