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Thursday, November 22, 2012

IF YOU FIND THE AREA........LETS WATCH....

MORE ABOUT AREA AND PERIMETER

http://www.bgfl.org/custom/resources_ftp/client_ftp/ks2/maths/perimeter_and_area/index.html

AREA


Area of a Square

1 square centimetre
The area of a square that has a side-length of 1 cm is 1 square centimetre (or 1 cm2).  To find the area of a square by the method of counting squares, we divide the square into smaller squares of one centimetre side-length .
Consider a square that has a side-length of 4 cm.
4 rows of 4 squares
Using the method of counting squares, we find that the area of the square is 16 cm2.
Clearly, the square contains 4 rows of 4 squares.  Therefore:
Area equals 16 square centimetres

This suggests that:
The area of a square is equal to its side-length multiplied by its side-length.  That is:
Area equals length squared

Using the pronumerals A for area and s for side-length, we can write it simply as:
Area equals s squared
This is the formula for the area of a square.


Example 1

Find the area of a square flower-bed of side 15 m.
Solution:
Area is 225 square metresSquare of side-length 15 m

Note:
To find the area of a region enclosed within a plane figure, draw a diagram and write an appropriate formula.  Then substitute the given values and use a calculator, if necessary, to obtain the required area.

Perimeter


A square and an equilateral triangle are both examples of regular polygons. Another method for finding the perimeter of a regular polygon is to multiply the number of sides by the length of one side. Let's revisit Examples 3 and 4 using this second method.

Example 3:Find the perimeter of a square with each side measuring 2 inches.[IMAGE]
Solution:This regular polygon has 4 sides, each with a length of 2 inches. Thus we get:
 P = 4(2 in) = 8 in

Example 4:Find the perimeter of an equilateral triangle with each side measuring 4 centimeters.[IMAGE]
Solution:This regular polygon has 3 sides, each with a length of 4 centimeters. Thus we get:
 P = 3(4 cm) = 12 cm

Example 5:Find the perimeter of a regular pentagon with each side measuring 3 inches.[IMAGE]
Solution:P = 5(3 in) = 15 in

Example 6:The perimeter of a regular hexagon is 18 centimeters. How long is one side?[IMAGE]
Solution:P = 18 cm
 Let s represent the length of one side. A regular hexagon has 6 sides, so we can divide the perimeter by 6 to get the length of one side (s).
 s = 18 cm ÷ 6
 s = 3 cm

Summary:To find the perimeter of a polygon, take the sum of the length of each side. The formula for perimeter of a rectangle is: P = 2L + 2W. To find the perimeter of a regular polygon, multiply the number of sides by the length of one side.