MAD: Calculate The Perimeter of These Polygons. Remember To Include Units!

11.
1 Perimeter of Polygons
The perimeter of a shape is the distance around the outside
of a polygon.
A polygon is a three or more sided shape
In the first example, the polygon is a rectangle. The

perimeter of the rectangle is the distance of the four sides:
3 + 5 + 3 + 5 = 2 x 3 + 2 x 5 = 2(3 + 5) = 16cm
Compound shapes are two or more polygons joined together.

You will need to find the missing lengths: 8cm
1. The missing vertical height is 11cm – 3cm = 8cm
2. The missing horizontal length is 10cm – 6cm = 4cm
4cm
Perimeter = 11 + 6 + 8 + 4 + 3 + 10 = 42cm
MAD: Calculate the perimeter of these polygons. Remember to include units!

11.1 Perimeter of shapes (grid)
When finding the perimeter

4 - We need to count the length.
- For example, the red rectangle has a
height of 3 and a base of 4. I can add
3 3 all of the lengths of together.
- 4 + 3 + 4 + 3 = 14cm
1
- The Blue L shape, I need to count all
4 2 the lines around it
- 1 + 2 + 1 + 1 + 2 + 3 = 10cm
3 1
1
2
MAD: Calculate the perimeter of these polygons. Remember to include units!

1)
2)
11.2 I can find area by counting squares
Using grid paper, we can find a value of area by counting the
number of squares that are inside a shape
1. Blue Shape
1. The blue shape is made up of three individual
squares that are next to each other.
2. The area of the blue shape is 3 square units
2. Black Triangle
1. The black triangle is half the area of a rectangle
2. The rectangle would be 2 squares wide by 3 squares
high
3. Area of black triangle = ½ x 3 x 2 = ½ 6 =
3 square units
3. Yellow Triangle
1. The yellow triangle is half the area of a rectangle
2. The rectangle is 1 square by 3 squares
3. Area of yellow triangle = ½ x 1 x 3 = 1 ½ square units
MAD: Find the area of these shapes by counting squares. Remember to include units!
11.3 I can analyse the effect of combining shapes on perimeter and area
A Compound shape is a shape formed when two or more polygons are
joined together to make a new shape
When joining compound shapes, the area will be equal to the sum of the
shapes used
The perimeter will be equal to the perimeter minus the number of units
that are shared between the two shapes joined together
In the example AREA = Area of Red + Area of Blue

Area = 5 square units + 7 square units = 12 square units
Perimeter = Perimeter of Red + Perimeter of Blue – shared side lengths
Perimeter = 12 units + 12 units – 8 Units = 16 units
Remember to count the shared units on both polygons!
MAD: Find the area and perimeter of these compound shapes.

11.4 I can explore area and perimeter of rectangles
The area of a rectangle is given by the formula:
3 cm

Area = Length x Width
In the rectangle on the right, the length = 4cm and the width
= 3cm
Using our formula:

4 cm

Area = 4cm x 3cm = 12cm2
Area is always measured in units squared!
MAD: Calculate the areas of these rectangles
MAD: Calculate the areas of these squares
MAD: What are 2 possible length and width combinations for rectangles with areas of:
10cm2 16cm2 15cm2 30cm2

1:
2:
11.4 I can calculate area of rectilinear shapes
A rectilinear shape is a shape where all sides meet at right angles
To calculate the area of rectilinear shapes, you can split the shape up
into two or more rectangles
A
Area of compound shapes will be the sum of all shapes used so just B
need to add the rectangles together to find the total area
In the shape on the right. I can split it into rectangles A and B
Rectangle A has length 10cm and width 9cm. Area of A = 10 x 9 =

90cm2
Rectangle B has length 10cm – 4cm = 6cm. Width = 12cm – 9cm = 3cm.
Area = 6cm x 3cm = 18cm2
Area = A + B = 90cm2 + 18cm2 = 118cm2
MAD: Calculate the areas of these rectilinear shapes
MAD: Calculate the area of the yellow shaded section

11.6 I can calculate the area of a parallelogram

The area of a parallelogram is given by the formula:
A = Area
b = base
hv = vertical/perpendicular height
Make sure to use the perpendicular height and not the slant height!
MAD: Calculate the area of the parallelograms drawn on cm square paper
MAD: Calculate the area of the parallelograms
MAD: Calculate the missing value in the parallelogram

11.7 I can calculate the area of a triangle

The area of a triangle is half the size of the
area of the rectangle around it
The formula is:
A = Area
b = base
hv = vertical/perpendicular height
For all the triangle above the base is 6

squares and the perpendicular height is 3
squares
MAD: Calculate the area of the triangles

MAD: Calculate The Perimeter of These Polygons. Remember To Include Units!

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11.

A polygon is a three or more sided shape

In the first example, the polygon is a rectangle. The

Compound shapes are two or more polygons joined together.

MAD: Calculate the perimeter of these polygons. Remember to include units!

When finding the perimeter

MAD: Calculate the perimeter of these polygons. Remember to include units!

In the example AREA = Area of Red + Area of Blue

Perimeter = Perimeter of Red + Perimeter of Blue – shared side lengths

Perimeter = 12 units + 12 units – 8 Units = 16 units

Remember to count the shared units on both polygons!

MAD: Find the area and perimeter of these compound shapes.

Area = Length x Width

Using our formula:

Area = 4cm x 3cm = 12cm2

Area is always measured in units squared!

MAD: Calculate the areas of these rectangles

MAD: Calculate the areas of these squares

10cm2 16cm2 15cm2 30cm2

In the shape on the right. I can split it into rectangles A and B

Rectangle A has length 10cm and width 9cm. Area of A = 10 x 9 =

Area = A + B = 90cm2 + 18cm2 = 118cm2

MAD: Calculate the areas of these rectilinear shapes

MAD: Calculate the area of the yellow shaded section

MAD: Calculate the area of the parallelograms drawn on cm square paper

MAD: Calculate the area of the parallelograms

MAD: Calculate the missing value in the parallelogram

The formula is:

For all the triangle above the base is 6

MAD: Calculate the area of the triangles

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