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Rh area of the 5&Prime; circle by the area of the 5&Prime; square. Is your answer .7854? If you should try this experiment with a circle of any diameter you would get the same result. Therefore, by squaring the diameter of any circle and multiplying by .7854, you can find its area. You will often see this rule written $$\scriptstyle{A=D^2\times.7854}$$. Does the method of arriving at this result resemble the one employed in establishing the rule for finding the circumference of a circle? In each case did we divide one quantity by another? Dividing one quantity by another establishes a comparison of the size of one to the size or the other. This comparison is called a ratio. For instance, the ratio of the foot to the inch is 12, and is found by dividing the foot by the number of inches in a foot. What is the ratio of the yard to the foot?

Problem 6D.—What is the area of the pattern for the bottom of the half-pint cup, Fig. 48. Compute the area of a 7&Prime; circle. Compute the area of an 8&Prime; circle. Compute the area of a 9⅞&Prime; circle.