9-6
MAIN IDEA
I will identify, describe,
and classify
quadrilaterals.
New Vocabulary
Quadrilaterals
There are many
quadrilaterals in
these fields. How
can you describe
some of the
different figures?
All quadrilaterals have 4 sides and 4 angles.
rectangle
square
rhombus
parallelogram
trapezoid
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Quadrilaterals
Key Concepts
A rectangle has 4 right angles with
opposite sides equal and parallel.
A square has 4 right angles with
opposite sides parallel. All sides
are equal in length.
A rhombus has 4 equal sides with
opposite sides parallel.
These marks
show equal
sides.
A parallelogram has opposite sides
equal in length and parallel.
A trapezoid has exactly 1 pair of
parallel sides.
EXAMPLE
Classify a Quadrilateral
1 Classify the quadrilateral in as many
ways as possible.
It can be classified as a parallelogram,
rectangle, square, and rhombus.
376
Chapter 9 Identify and Describe Geometric Figures
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Many real-world objects have the shapes of quadrilaterals.
Real-World EXAMPLES
Real-World Shapes
2 VIDEO GAMES Write the type
of quadrilateral that best
describes the shape around
the game controller.
The shape has one
pair of parallel sides.
So, it is a trapezoid.
3 Identify the red shape in as
many ways as possible.
The shape has 4 right angles,
with opposite sides equal and
parallel. So, it is a rectangle
and a parallelogram.
Classify each quadrilateral in as many ways as possible.
See Example 1 (p. 376)
1.
2.
3.
Write the type of quadrilateral that best describes the shape.
See Examples 2–3 (p. 377)
4.
7.
5.
6.
How are a square and a rhombus alike? How are they
different?
Lesson 9-6 Quadrilaterals 377
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EXTRA
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See page R24.
Classify each quadrilateral in as many ways as possible.
See Example 1 (p. 376)
8.
9.
10.
11.
12.
13.
Write the type of quadrilateral that best describes the shape.
See Examples 2 and 3 (p. 377)
14.
15.
16.
17.
18.
19.
20. A quadrilateral has 4 sides with
opposite sides parallel and 4 right
angles. Two sides are longer than the
others. What is the quadrilateral?
21. Phillip draws a quadrilateral. All
4 sides are the same length. Its
opposite sides are parallel. What
figure did he draw?
22. OPEN ENDED Draw two quadrilaterals that can be classified
as parallelograms.
REASONING Tell whether each statement is true or false. If the
statement is false, draw a counterexample.
23. A rhombus is a square.
25.
378
24. A rectangle is a parallelogram.
True or false: All squares are rectangles,
but not all rectangles are squares. Explain.
Chapter 9 Identify and Describe Geometric Figures
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