or, instead of dividing the diameter by 3·1416, multiply it by ·3183, for the circumference.
Example 1.—Required, the circumference of a circle, whose diameter is 20 feet.
As 7 : 22 :: 20 : 62·857 feet. Circumference required.
Example 2.—Required, the diameter of a circle, whose circumference is 36 inches.
As 22 : 7 :: 36 : 11·45 inches. Diameter required.
To find the diameter of a circle, the area being given.
Divide the area by ·7854, and the square root of the quotient will be the diameter required.
Example.—Required, the diameter of a circle, whose area is 176·715 square feet.
176·715 ÷ ·7854 = 225.
Square root of 225 = 15 feet. Diameter required.
To find the area of a circle.