1. Areas of Flags 2

2. Starter
This is the Flag of Iceland. The ratio of height to base is 3:4. The red area is 20cm2 more than the white area. Calculate the area of each colour.
6cm
11cm
6cm
15cm

3. Areas of Flags 2
Learning Objectives All will be able to calculate the areas of Triangles and Parallelograms in the context of flags (Level 5/6) Most will be able to involve additional information in the questions (Level 6) Some will be able to include ratio and more advanced problem-solving skills in the questions (Level 6/7)

4. Areas of Flags 2 How could we calculate the area of this Triangle? 5cm

5. Base x Perpendicular Height
Areas of Flags 2
Area of a Triangle
Base x Perpendicular Height 2
11m
9cm
8cm 5m
3cm
B x H 2
3 x 8 2
B x H 2
5 x 11 2 = =
12cm2 = =
27.5m2

6. Areas of Flags 2
How could we calculate the area of this Parallelogram?
5cm
4cm
9cm

7. Base x Perpendicular Height
Areas of Flags 2
Area of a Parallelogram
Base x Perpendicular Height 2m 7m
6cm
7cm 5m
13cm
B x H =
13 x 6 =
78cm2
B x H =
2 x 5 =
10m2

8. Areas of Flags 2
This is the flag of Djibouti. The red star takes up 5% of the area of the white triangle. The white triangle’s tip is in the centre of the flag.
Calculate the area of each part of the flag.
12cm
20cm

9. Plenary

10. Summary
We have seen how to calculate the areas of Triangles and Parallelograms
We have again practised this in the context of flags!