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Area of a Circle Formula. The area of a circle is the total amount of space enclosed by its boundary or circumference. There is no volume in a circle because it is a flat, two-dimensional shape. If you know the radius of a circle, you can easily find its area.
The area of a circle can be found using the following formula: A = πr 2. where A is area, r is radius, and π is the mathematical constant approximately equal to 3.14159. Alternatively, if using the circle's diameter, D, the area is: Or, if using the circle's circumference, C, the area is:
Since the formula for the area of a circle squares the radius, the area of the larger circle is always 4 (or 2 2) times the smaller circle.Think about it: You are doubling a number (which means ×2) and then squaring this (ie squaring 2) -- which leads to a new area that is four times the smaller one.
The area of the first square is 7 2 = 49 and the area of the second square is 10 2 = 100 , so we know that the area of the circle must be between 49 and 100 . That narrows it down a bit, but we still don't know exactly what the area is.
Here the Greek letter π represents a constant, approximately equal to 3.14159, which is equal to the ratio of the circumference of any circle to its diameter. One method of deriving this formula, which originated with Archimedes, involves viewing the circle as the limit of a sequence of regular polygons.
The formula is: Area = w × h w = width h = height. We know w = 5 and h = 3, so: Area = 5 × 3 = 15. Example: What is the area of this circle? Radius = r = 3.
The area of a circle is calculated using the formula A = pr , where A is the area, p is the ratio of a circle's circumference to its diameter, and r is the radius of the circle. What is the Circumference of a Circle?
