Question

The corners of a square are cut off two centimeters from each corner to form an octagon. If the octagon is 10 centimeters wide, what is it's area?

Answer 1

Answer:

• 92 cm²

Explanation:

The area of the octagon may be calculated as the difference of the area of the original square and the area of the four corners cut off.

1) Area of the square.

The original square's side length is the same wide of the formed octagon: 10 cm.

So, the area of such square is: (10 cm)² = 100 cm².

2) Area of the four corners cut off.

Since, the corners were cut off two centimeters from each corner, the form of each piece is an isosceles right triangle with legs of 2 cm.

The area of each right triangle is half the product of the legs (because one leg is the base and the other leg is the height of the triangle).

Then, area of one right triangle: (1/2) × 2cm × 2cm = 2 cm².

Since, they are four pieces, the total cut off area is: 4 × 2 cm² = 8 cm².

3) Area of the octagon:

• Area of the square - area of the cut off triangles = 100 cm² - 8cm² = 92 cm².

And that is the answer: 92 cm².