Page 229 - SK Year 5 Mathematics DLP

PERIMETERS OF COMPOSITE SHAPES

1

Indung, we
have made
this bookmark Shanti, let’s decorate
out of these the outline of the
two regular bookmark with this
polygons. green-coloured
paper.

How do we determine the length of the green-coloured paper

that is needed?
The length of the 9 cm
green-coloured 9 cm
paper is the length
of the outer sides or
the perimeter of the 9 cm
composite shape.
9 cm

1 Measure all the 9 cm
outer sides of 9 cm 9 cm
the composite
shape. Perimeter = (9 + 9 + 9 + 9 + 9 + 9 + 9) cm
2 Total up the
length of all the = 63 cm
outer sides of the OR
composite shape. Perimeter = 7 × 9 cm

= 63 cm
The length of the green-coloured paper

9 cm needed is 63 cm.

Is the perimeter of the composite shape of this
regular polygon 63 cm as well? Discuss.

• Provide each group with a few regular polygon shapes. Each group must 221
6.3.1 form a composite shape from two polygons and determine the perimeter
of the composite shape.