Hi there! The answer is 100πcm^2
The radius of a circle can be found by dividing the diameter by 2. In other words : the radius is half of the diameter.
Therefore, the radius of a circle with a diameter of 20 cm is 10 cm.
The exact area of a circle can be found using the following formula:

In order to find our answer, we need to plug in the data from the question.

Hence, the answer is 100πcm^2.
Answer: The quadrilateral used here is a trapezium.
Mixed number form: h = - 1 2/13 Hope that helps :))