To find the diameter of the circle, we need to use the pythagorean theorem and use it on one of the triangles in the rectangle.
Pythagorean theorem: \(a^2+b^2=c^2\)
Lets replace a with 21 and b with 20 to get the equation \(21^2+20^2=c^2\)
Simplifying the left side gives us \(841=c^2\)
which means that \(c = \sqrt{841}\) which is exactly \(29\)
Now that we know the diameter of the circle, we can find the area.
The formula for the area of a circle is \(𝜋r^2\), r being the radius.
We can find the radius by dividing 29 by 2, 14.5
Using the formula, we get A ≈ 660.52
So the area of the circle is about 660.52
To find the area of the rectangle inside the circle, we multiply the length by the width.
21*20=420
Now we subtract 420 from 660.52
660.52-420 = 240.52