The formula for the area of a circle is a = πr², r being the radius.
To tackle this problem, find the area of the square and then subtract the area if the circle:
Area of square = 20 * 20 = 400
Area of circle = π(10)² = 100π = 314
Area of square - area of circle = 400 - 314 = 86 m²
Hope this helps!
