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Ms. D's Chapter 9 - Perimeter, Circumference and Area

The area of a polygon is the number of square units that the figure covers.  Area is measured in square units, such as square feet or square miles.  An example is the area of a square whose sides each measure 2 inches long -- the area is 2*2=4 square inches.

Area of a Rectangle

The area of a rectangle is the product of its length and width:  A = lw

Area of a Triangle

The area of a triangle is half the area of a rectangle -- half the product of a base and its corresponding height:  A = (1/2) bh

Area of a Parallelogram

A parallelogram is a  quadrilateral with two pairs of opposite sides that are parallel to each other.  Any side of a parallelogram can be called a base.  Each base has a corresponding altitude, and the length of the altitude is the height of the parallelogram.

The area of a parallelogram is equal to the area of a rectangle with the same base and height as the parallelogram -- the area of a parallelogram is the product of a base and its corresponding height:  A = bh

Area of a Regular Polygon

In a regular polygon, all sides are congruent and all angles are congruent.  You can find the area of the regular polygon if you know the length of one side of the polygon and the length of the apothem.  The apothem is the perpendicular segment from the center of a regular polygon to one of its sides -- the length of the apothem is the height of the triangle formed by a side and the two segments from the center to the endpoints of this side.  The area of a regular polygon is half the product of the apothem (a) and the perimeter (P):  A = (1/2) a*P

Another way to look at the formula for area of a regular polygon is to find the area of one the triangles found in the polygon and multiplying by the number of sides in the polygon:  A = (1/2) bh * n, where h is the height of the triangle (the apothem of the polygon), b is the length of one side of the polygon and n is the number of sides of the polygon.

tester » 6am - Mar 30, 2011
This video shows you how to find the area of a regular hexagon if...

## Area of a Regular Hexagon Ch 9 Test Review

Area of a Quadrilateral with Perpendicular Diagonals

To find the area of a quadrilateral that has perpendicular diagonals (such as rhombus, square, and kite), find the half the product of the diagonals:  A = (1/2) d1*d2

Area of a Trapezoid

The area of a trapezoid is half the product of the height and the sum of the bases:  A = (1/2) h*(b1 + b1)

tester » 7am - Mar 30, 2011
This video shows you how to find the area of a circumscribed...

## Area of a Trapezoid Ch 9 Test Review

Visit www.msdgeometry.com -  your ultimate internet resource for comprehensive information on High School Geometry, Algebra, and Trigonometry.

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In this chapter, your child will learn to develop geometric formulas for calculating the perimeter, circumference, and area of a variety of shapes.

Your child will also learn the special properties of a circle. Your child will learn to calculate the area and circumference of a circle.

Your child will also learn to determine the area of composite figures. A composite figure is made up of simple shapes such as triangles, rectangles, trapezoids, and circles. In order to find the area of these shapes, the area of each simple shape must be determined and then the areas added together.

The last thing your child will cover in this chapter is geometric probability. This is the probability of an event based on a ratio of geometric measures such as length or area.

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 Click on the links to watch short tutorials and take interactive quizzes: * 9-5 Effects of Changing Dimensions Proportionally, pp. 622 - 627 video #1, video #2, video #3, video #4, Interactivity, Practice Quiz 9-5  * 9-3 Areas of Composite Figures, pp. 606 - 612 * 9-3 Areas of Composite Figures, pp. 606 - 612

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For help with the Skill Builder 3 Packet, you can use the videos below.  An electronic copy of the packet it attached.

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 1

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 2

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 3

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 4

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 5

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 6

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 7

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 8

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 9

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 10

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter

## Skill Builder 3 Part 11

tester » 12pm - Sep 23, 2012
Unit 3 Review for Geometry A - Area and Perimeter