Page 230 - SK Year 5 Mathematics DLP

4 m
2
4 m 4 m
end 10 m

4 m start
Determine one
4 m 10 m side as a starting
4 m point to calculate.
4 m 6 m

10 m
Method 1 Perimeter = (10 + 10 + 6 + 4 + 4 + 4 + 4 + 4 + 4 + 4 + 10) m

= 64 m

+
Method 2 Perimeter = Perimeter of the outer Perimeter of the outer
sides of the octagon sides of the square

= (7 × 4 m) + (10 m + 10 m + 10 m + 6 m)
= m + m
= m

3 Determine the perimeter of the shaded region.

start
Perimeter of the shaded region Total up the
6 cm surrounding sides of
= (6 + 6 + 5 + 6 + 5 + 6 + 6) cm the shaded region.

= cm 6 cm

5 cm
5 cm

4 m
4
Discuss the error in
1 m calculation of this perimeter.

Perimeter of the shaded region
2 m 5 m
(4 + 5 + 2 + 1 + 1) m = 13 m

222 • Carry out exploration activities of two composite shapes using regular
6.3.1 polygons including triangles and quadrilaterals to find perimeter.