Question

The polygons are regular polygons. Find the area of the shaded region to the nearest tenth.

Answer 1

Answer:

128.8 cm²

Step-by-step explanation:

In the image attached below, the regular polygon is a square which is composed of a small square and a large square. In a square, all the sides are equal.

For the small square, half of the diagonal is 4 cm, therefore the length of the diagonal is 8 cm (2 × 4 cm). Let the length of the side be a cm, using Pythagoras theorem:

a² + a² = 8²

2a² = 64

a² = 32

a = √32 = 5.7 cm

The area of the small square = length × length = 5.7 × 5.7 = 32.5 cm²

For the large square, half of the diagonal is 9 cm, therefore the length of the diagonal is 18 cm (2 × 9 cm). Let the length of the side be b cm, using Pythagoras theorem:

b² + b² = 18²

2b² = 324

b² = 162

b = √162 = 12.7 cm

The area of the large square = length × length = 12.7 × 12.7 = 161.3 cm²

The area of the shaded region = Area of large square - Area of small square = 161.3 cm² - 32.5 cm² = 128.8 cm²