If each square in the circle to the left has an area of 1 cm 2 you could count the total number of squares to get the area of this circle. The result will vary from zero when the height is zero to the full area of the circle when the height is equal to the diameter. Visual on the figure below.
Area of a Circle.
We know w 5 and h 3 so. P Pi times the Radius squared. Lets look at. The Circle Formulas are expressed as Diameter of a Circle.