Question

The diagram below shows a square inside a regular octagon. The apothem is of the octagon is 13.28 units. To the nearest square unit, what is the area of the shaded region?

Answer 1

I found the image of this problem. Its side measure is 13. The octagon can form 8 triangles. Its apothem can serve as the height of the triangle. We need to get the area of the triangle and multiply it by 8. We then deduct the area of the square from the total area.

Area of a triangle = (height * base) / 2

A = (15.69 * 13) / 2

A = 203.97 / 2

A = 101.985 sq. units

101.985 x 8 = 815.88 sq. units

Area of the square = s²

A = 13²

A = 169 sq. unit

Area of the shaded region: 815.88 sq. unit - 169 sq. unit = 646.88 sq. unit

Explanation: