Perimeter The perimeter of a shape is the

Perimeter The perimeter of a shape is the distance around the outside. Rectangles 15 m Length 5 m Width 5 m 15 m Perimeter = 15 m + 5 m = 40 m

Essential working Example 4 cm Perimeter = 4 + 7 + 4 + 7 = 22 cm Perimeter = 8 + 14 = 22 cm 7 cm Perimeter = 2 x 11 = 22 cm Perimeter = 2 x 4 + 2 x 7 = 22 cm There a few alternative ways of getting the correct answer.

Find the perimeter of each rectangular shape below. 100 m 1 2 50 m 90 feet 280 ft 300 m 50 feet 40 m 3 4 120 m 8½ cm 600 cm = ? 5 320 m Not to scale. 5½ cm 90 cm 28 cm 210 cm

To find the perimeter of a shape we add together the length of all the sides. What is the perimeter of this shape? Starting point Perimeter = 3 + 2 + 1 + 2 3 = 12 cm 2 3 1 1 2 1 cm

Sometimes we are not given the lengths of all the sides. We have to work them out using the information we are given. 9 cm What is the perimeter of this shape? 5 cm The lengths of two of the sides are not given 12 cm 4 cm so we have to work them out before we can a cm find the perimeter. Let’s call the lengths a and b. b cm

Sometime we are not given the lengths of all the sides. We have to work them out from the information we are given. 9 cm a = 12 – 5 cm = 7 cm 5 cm b = 9 – 4 cm = 5 cm 12 cm 4 cm a cm 7 P = 9 + 5 + 4 + 7 + 5 + 12 = 42 cm b cm 5

Calculate the lengths of the missing sides to find the perimeter. 5 cm p = 2 cm p q r s s = 6 cm t = 2 cm 6 cm 4 cm t q = r = 1. 5 cm u = 10 cm 4 cm 2 cm u 2 cm P = 5 + 2 + 1. 5 + 6 + 4 + 2 + 10 + 2 + 4 + 6 + 1. 5 + 2 = 46 cm

What is the perimeter of this shape? 5 cm 4 cm Remember, the dashes indicate the sides that are the same length. P=5+4+4+5+4+4 = 26 cm

What is the perimeter of this shape? Start by finding the lengths of all the sides. 4. 5 m 5 m Perimeter = 4. 5 + 2 + 1 + 2 + 4. 5 4 m = 17 m 2 m 1 m 2 m

What is the perimeter of this shape? Before we can find the perimeter we must convert all the lengths to the same units. 256 cm 3003 cm m 1. 9 m 190 cm In this example, we can either use metres or centimetres. Using centimetres, 2. 4 m 240 cm P = 256 + 190 + 240 + 300 = 986 cm

Which shape has a different perimeter from the first shape? A B C B C A C