# Area and Perimeter.

## Presentation on theme: "Area and Perimeter."— Presentation transcript:

Area and Perimeter

Perimeter Perimeter is the distance around the outside of the object
To find a perimeter we _____ up the ________ e.g. Perimeter = ___ + ___ + ___ + ___ + ___ = ___

Perimeter Perimeter is the distance around the outside of the object
To find a perimeter we add up the sides e.g. Perimeter = ___ + ___ + ___ + ___ + ___ = ___

Perimeter Perimeter is the distance around the outside of the object
To find a perimeter we add up the sides e.g. Perimeter = = 44

P= P= P=

P= 50 P= 25cm P= 34m

Area Area is the surface an object has. How much flat space it takes up. Each type of shape has its own rules. The unit for area is the unit for the side with a squared sign. cm  cm2 m  m2 km  km2

Rectangles and Squares
Rectangles and squares follow the basic rule about area. AREA = WIDTH x HEIGHT 8 A = ___ x ___ = ___

Rectangles and Squares
Rectangles and squares follow the basic rule about area. AREA = WIDTH x HEIGHT 8 A = x 8 = 32

A = _________________

A = 3 x 17 = 51m2 A = 10 x 52 = 520cm2 A = 50 x 70 = 3500km2

Cut the shape into two rectangles with a line.
Now you have 2 rectangles. You can calculate the area of each rectangle. Top rectangle 18 x 10 = 180 Bottom rectangle 9 x 12 = 108 Total Area = 288 Unit is cm2 A = 288cm2

What is the perimeter and area of this shape?

What is the perimeter and area of this shape?

Parallelograms Parallelograms are just like rectangles
AREA = WIDTH x HEIGHT You must be careful about the number you use for height. The height of this parallelogram is not ___ it is ___. This is because the ___ is on a lean.

Parallelograms are just like rectangles
AREA = WIDTH x HEIGHT You must be careful about the number you use for height. The height of this parallelogram is not 8 it is This is because the 8 is on a lean.

7m 6cm 4cm 8cm 12m 5m

Triangles Triangles don't stay the same width the whole way across.
Two triangles can make a rectangle so each triangle is half as much area as the rectangle. AREA = ½ x WIDTH x HEIGHT 7 10 A =__ x __ x __ = __

Triangles don't stay the same width the whole way across.
Two triangles can make a rectangle so each triangle is half as much area as the rectangle. AREA = ½ x WIDTH x HEIGHT 7 10 A = ½ x 7 x = 35

Trapeziums Like a triangle the width of a trapezium changes.
We have to work out the average width. 8 14 A = (a + b) x h A = ( __ + __ ) x __ Average Width = (top side + bottom side) ÷ 2

Like a triangle the width of a trapezium changes.
We have to work out the average width. 8 14 A = (a + b) x h A = ( ) x 6 = 66 Average Width = (top side + bottom side) ÷ 2

Circles To find the area of a circle you need the radius.
The radius is the distance from the ________ of the circle to the _________. middle outside radius

To calculate the area use the formula
π is just a number ( ) You have a calculator button for it. Multiply it by the radius then multiply it by the radius again. You will need to round your answer.

e.g. A = π r2 = x 3 x 3 = 28.27m2 3m

To find the perimeter of a circle (also called circumference) you need to use the formula P = 2 π r

e.g. P = 2 π r = 2 x x 3 = 18.85m 3m