Page 109 - NUMINO Challenge_A2
P. 109
Answer
Key
Type Study Perimeter of Concave Polygons
1 Move the sides of the concave shape to make a rectangle. The remaining sides are
shown in red.
AD
a b
5 cm C
B
10 cm
2 Perimeter of the Figure (Perimeter of the Rectangle) (Length of a) (Length of b)
Therefore, you will need to find side AB or side DC.
Problem solving
1 Move the side of the inverted portions to make a square as shown below.
(Perimeter of the Figure) (Perimeter of the Square) (Sum of the Lengths of Eight Bold Lines)
5 5 5 5 8 28 cm
2 Compare the perimeters of the two figures with the perimeter of a square:
(5 4) (4 2) 28 cm (5 4) (4 4) 36 cm
4 NUMINO Challenge A2
Key
Type Study Perimeter of Concave Polygons
1 Move the sides of the concave shape to make a rectangle. The remaining sides are
shown in red.
AD
a b
5 cm C
B
10 cm
2 Perimeter of the Figure (Perimeter of the Rectangle) (Length of a) (Length of b)
Therefore, you will need to find side AB or side DC.
Problem solving
1 Move the side of the inverted portions to make a square as shown below.
(Perimeter of the Figure) (Perimeter of the Square) (Sum of the Lengths of Eight Bold Lines)
5 5 5 5 8 28 cm
2 Compare the perimeters of the two figures with the perimeter of a square:
(5 4) (4 2) 28 cm (5 4) (4 4) 36 cm
4 NUMINO Challenge A2
