Page 127 - Math Course 1 (Book 2)

Geometric Area: Parallelogram

MO. 10 - L4b
Let’s Begin
Parallelogram on a
Coordinate Plane

Perimeter and Area on the Coordinate Plane
Vocabulary A-Z Examples
Let us learn some vocabulary

A. The vertices of a quadrilateral are A(–2, 3),
B(4, 1), C(3, –2), and D(–3, 0). Determine
height of a parallelogram whether the quadrilateral is a square, a
rectangle, or a parallelogram.
The length of an altitude is called the
height of the parallelogram.

A(–2, 4)
B(4, 1)

altitudes

D(–3, 0)

C(3, –2)
base

First graph each point and draw the quadrilateral.
Then determine the slope of each side.

3 – 1
Slope of AB =
–2 – 4
2 1
= or –
base –6 3
altitudes
–2–0
Slope of CD =
3–(–3)
2 1
= or –
–6 3

1–(–2)
Slope of BC =
4 – 3
3
= or 3
1

3 – 0
Slope of AD =
-2 – (- 3)
3
= or 3
1

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