## Area, Perimeter, and circumference

Overview: In this lesson you will learn how to find the area of shapes, the circumference of shapes and the perimeter of shapes.

## How to find the area of shapes

Area: space inside of a shape.

To find area you use the method length times width equals area or L•W=A

Definition: the inside space of a two-dimensional figure.

To find area you use the method length times width equals area or L•W=A

Definition: the inside space of a two-dimensional figure.

## What an area problem looks like

Area=Length•Width. Important numbers21 & 53

Fill in variable letters (L,W). L•W=?

53=L

21=W

Answer: 53•21=113 inches.

Fill in variable letters (L,W). L•W=?

53=L

21=W

Answer: 53•21=113 inches.

## How to Find the Perimeter of Shapes

Perimeter: Outer boundary of a shape. (not a circle) To find area you use the method L+W+L+W=P.

Definition:the border or outer boundary of a two-dimensional figure.

Definition:the border or outer boundary of a two-dimensional figure.

## What a perimeter problem looks like

Perimeter=L+W+L+W

Important numbers:73,& 73.

variable numbers. (L,W,L, and W).

Variable problem is L+W+L+W=?

L=50

W=73

50+73+50+73=246 inches.

Important numbers:73,& 73.

variable numbers. (L,W,L, and W).

Variable problem is L+W+L+W=?

L=50

W=73

50+73+50+73=246 inches.

## How to find the circumference

Circumference: the distance AROUND the circle

Definition:the outer boundary, especially of a circular area; perimeter:

C=pi•diameter

Definition:the outer boundary, especially of a circular area; perimeter:

C=pi•diameter

## What a circumference problem looks like

2 different ways to find the circumference: pi (3.14) times the diameter,second is 2 times pi (3.14) times radius

Radius is half the size of the diameter and the diameter is 2 times larger than the radius.

Radius is half the size of the diameter and the diameter is 2 times larger than the radius.

## Diameter and Radius example problems

2 ways to find the circumference:

pi•D

pi•R

Option number one example: 3.14•16 (diameter)

Option number two example:2•3.14•8 (radius)

Option number one answer: 50.24

Option number two answer: 50.24

Do you see the resemblance? :)

pi•D

pi•R

Option number one example: 3.14•16 (diameter)

Option number two example:2•3.14•8 (radius)

Option number one answer: 50.24

Option number two answer: 50.24

Do you see the resemblance? :)