Shape and Space - part 1 PERIMETER A If you want to put a border around the edge of a poster or a room, you need to find the perimeter. To find the perimeter you add the measurements of all the sides. Example: 4cm 3cm 3cm 4cm The perimeter of this rectangle = 4 + 3 + 4 + 3 cm = 14cm A) 1) Try measuring the sides of each of these shapes in centimetres and add them up to find the perimeter: 2) 3) 4) 5) f lex i p 6) ac k s 1 Shape and Space - part 1 7) 8) 9) 10) 11) 13) f lex i p 12) ac k s 2 Shape and Space - part 1 The diagrams in the next questions are not drawn to the right size. Example: 14m 10m 11m 16m This children’s playground is to have a fence round the outside. How long will it be? 14 m + 11 m 16 m 10 m 51 m Answer 51 m long B) Try these questions: (don’t forget you don’t need to measure). What length of border is needed for these play areas? 1) 40m 30m 2) 45m 30m 50m 50m 40m 3) 20m 20m 60m 20m 4) 20m 118m 20m 40m 40m 20m f lex i p 121m ac k s 3 Shape and Space - part 1 Sometimes the diagram may not show all the side lengths. It’s easier if you write them on yourself. Example: 15m 9m The length of this hall is 15m. The width is 9m. Write these measurements in: 15m Perimeter = 15m 15m 9m 9m 9m 15m 48m C) 9m The perimeter = 48m Try these: What length of wood will be needed to make frames for these photos? 1) 40cm 2) 18cm 28cm 13cm 3) 50cm 4) f lex i p 40cm ac k s 45cm 65cm 4 Shape and Space - part 1 You could try drawing a sketch for these questions: 5) Nathan is fixing a picture rail round a room which is 6m long and 5m wide. What length will he have to buy? 6) Jenny has to put a fence all round a garden which is 22m long and 11m wide. How many metres of fencing does she need? 7) A cushion cover needs ribbon piping round the edge - the cover is 30cm square. How much will be used? Is one metre enough? 8) A gutter runs all round a roof which is 15m long and 12m wide. What length is the gutter? f lex i p Check your answers then discuss with your tutor what you need to work on next. ac k s 5 Shape and Space - part 1 Answers Perimeter A B) A) C) 1) 16cm 1) 140m 1) 136cm 2) 20cm 2) 205m 2) 62cm 3) 20cm 3) 120m 3) 180cm 4) 20cm 4) 319m 4) 220cm 5) 24cm 5) 22m 6) 22cm 6) 66m 7) 20cm 7) 120cm 8) 24cm 8) 54m 9) 30cm 10) 32cm 11) 18cm 12) 16cm f lex i p 13) 20cm ac k s 6 not enough Shape and Space - part 1 PERIMETER B Re-cap: the perimeter is the distance around the edge of a shape. If the measurements you’re using have decimal fractions, check that you line up the decimal points when you add. Whole numbers are best written with a decimal point - e.g. 6cm can be written 6.0cm. Example: 4.6cm 4.6 4.6 2.5 + 2.5 14.2cm 2.5cm The perimeter = 14.2cm A) Try measuring the sides of these printing blocks in centimetres to find the perimeter: a 1) 2) m 4) f lex i p 3) A ac k s M 7 Shape and Space - part 1 Complex Shapes In more complex shapes, you still need to add all the side measurements. 3m Example: 3m 3m 5m 2m 6m Make a mark where you mean to start, so you don’t forget where you’re up to. The perimeter = 3 + 5 + 6 + 2 + 3 + 3 m = 22 m B) Try finding the perimeters of these shapes: The diagrams are not drawn to the right size. 1) 4cm 2) 2cm 10m 3m 3cm 5cm 3cm 7m 8m 7cm 5m 3m 2mm 12in 3) 4) 10mm 10mm 4in 10in 6mm 3mm 4mm 7in f lex i p 7in 4mm 11mm ac k s 10in 3in 8 5in Shape and Space - part 1 Sometimes you may need to work the measurements out for yourself in complex shapes. Example: To find the perimeter of this room, you also need to know what side is. s 15m 6m 10m s 4m 8m But the whole of the bottom edge must be 15m, the same as the top. 15m 6m 10m s=7 4m 8m 15m So side s must be 7m (15 - 8) The perimeter = 15 + 10 + 8 + 4 + 7 + 6 m = 50 m C) Try these questions: Find the perimeter of these rooms to see what length of carpet gripper is needed: Make sure you write the length on all the sides. f lex i p (see over) ac k s 9 Shape and Space - part 1 1) 2) 10m 8m 6m 12m 5m 2m 4m 2m 2m 2m 5m 3) 4) 4m 10m 4m 6m 5m 12m 2m 2m 5) 4m 6) 4.8m 4m 3m 6.5m 4m 2m 7.2m 4m f lex i p Check your answers then discuss with your tutor what you need to work on next. ac k s 10 Shape and Space - part 1 Answers Perimeter B A) C) B) 17.8 cm 1) 24 cm 1) 44 m 2) 18.8 cm 2) 36 m 2) 26m 3) 19.8 cm 3) 50 mm 3) 18 m 4) 24 cm or 24.0 cm 4) 58 in 4) 56 m 5) 17.6 m 6) 27.4 m f lex i p 1) ac k s 11