Areas of 2D Shapes

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Lesson 9-1
Area of 2-D Shapes
2
Squares and Rectangles
Area of Rectangle A LW
Area of Square A s²
A LW
Example
Example
A 12 x 5 60 sq. units
3
Circles and Sectors
Area of Circle A ? r²
9 cm
120
9 cm
Example
Example
A ?(9)² 81 ? sq. cm
4
Triangles and Trapezoids
h is the distance from a vertex of the triangle
perpendicular to the opposite side.
h is the distance from b1 to b2, perpendicular to
each base
5
Example Triangles and Trapezoids
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Parallelograms Rhombi

• Area of Parallelogram A b ?h

h
b
Example
Example
A 9 x 6 54 sq. units
A ½ (8)(10) 40 sq units
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Area of Regions
The area of a region is the sum of all of its
non-overlapping parts.
A ½(8)(10) A 40
A (12)(10) A 120
A (4)(8) A32
A (14)(8) A112
Area 40 120 32 112 304 sq. units
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Areas of Regular Polygons
If a regular polygon has an area of A square
units, a perimeter of P units, and an apothem of
a units, then A ½ (a)(p).

• Perimeter (6)(8) 48
• apothem
• Area ½ (48)( ) sq. units

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