Page 108 - NUMINO Challenge_A2

Problem solving

1 Think about how you found the perimeter of connected shapes.

3 33
2 22 22
202
101 21112
101 101
101 101
31113 212

24 cm 30 cm

2

Sum of the Lengths of the Blue Lines
(Four Sides of the Rectangle) (Two Sides of the Triangle) 8 4 4 cm

Perimeter of the Figure
(One Side of the Triangle) 6 (One Side of the Rectangle) (Sum of the Lengths of the
Blue Lines)
2624
18 cm

Investigate2. Perimeter of Concave Polygons Perimeter of Concave Polygons

Forming Shapes with Matchsticks

Figure A

Number of 2 4 4 2 2
Added
Matchsticks

Perimeter (cm) 14 16 16 14 14

When the square is changed into a concave
polygon, the perimeter of the shape increases by
the sum of the lengths of the inverted portions.

3Answer Key