Area of Shapes

This Photo by Unknown author is licensed under CC BY-SA.

I can...
• Use formulas to find area of triangles, quadrilaterals, and
polygons

• Find the surface area using rectangles and triangles

The area of a rectangle is the
product of its length ℓ and its
width w.

The area of a polygon is the
amount of surface it covers.
You can find the area of a
parallelogram in much the
same way as you can find the area of a rectangle.

Find the area of the rectangle

NOTE: The base of a parallelogram does not have to be horizontal.
Any side of a parallelogram can be the base.

Area of a Parallelogram
Words
The area A of a parallelogram is the product of its base b and its height h.

A = base x height
A = b * h
Sometimes we refer to the base and height as the length and width
A = length x width
A = l * w

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The side of an office building in Hamburg, Germany, is in the shape of a parallelogram. The area of the side of the building is about 2150 square meters. What is the length of the base of the parallelogram if the height is 25 meters?

- 25 m

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Areas of
Triangles

Areas of

Trapezoids

A trapezoid is a 4-sided flat shape with straight sides that has a pair of opposite sides parallel

Areas of Kites

A kite is a quadrilateral that has two pairs of adjacent sides with the same length and opposite sides with different lengths.

Use the measurements
and apply the
formula for the area of triangles
to find the area of both triangles. The sum of the areas is the area of the kite

Irregular Polygons
(Composite Shapes)

Areas of

Composite

Figures

Quadrilaterals are polygons that have four sides. There are many different types of quadrilaterals. In this unit, we are focusing on quadrilaterals that are squares, rectangles, parallelograms, trapezoids, and kites.

What makes these quadrilaterals different from one another? (see next slide)

Only one pair of parallel sides

Two pairs of parallel sides

Four right angles

All sides
congruent

Two pairs of congruent sides

Squares

Rectangles

Parallelograms

Trapezoids

Kites