You have to calculate the radius - half the diameter. Then square the radius, and multiply by pi (approximately 3.1416). If you want to do a mental estimate, round pi to 3.
The circumference of a circle that has a diameter of 6.75 feet is about 21.2 feet.
Estimate: 3*10 = 30 inches Actual: pi*9.8 = 30.788 inches rounded to three decimal places
Estimate: 3*40 = 120 inches Actual: pi*39 = 122.5 inches to one decimal place
Seven inches.
The thickness of any U.S. coin is measured at the rim. For dimes it's 1.35mm.
The best estimate for the circumference of a circle that has a diameter of 6 is 18.9
The circumference of a circle that has a diameter of 6.75 feet is about 21.2 feet.
The 'best' estimate of the area of a circle with a radius of 7.62 meters is: 182.414692 m2
The radius of a circle is halve the circle's diameter.
50.26548246 Inches 127.6743254 Centimetres
When the diameter of a circle is halved, the radius is also halved since the radius is half of the diameter. The area of a circle is calculated using the formula A = πr^2, where r is the radius. If the radius is halved, the area is reduced to one-fourth of its original size because the radius is squared in the formula. Therefore, halving the diameter of a circle results in the area being reduced to one-fourth of its original area.
Estimate: 3*10 = 30 inches Actual: pi*9.8 = 30.788 inches rounded to three decimal places
Estimate: 3*40 = 120 inches Actual: pi*39 = 122.5 inches to one decimal place
The length of a chord that contains the center of the circle
milimeters
The diameter of a circle is twice its radius or its largest chord passing through the center of the circle.
The Circumference of a circle (C) equals the number "pi" times the diameter of the circle (d). "pi" (3.14159...) is a number which you can never find the value of precisely, the numbers after the decimal point go on for ever. Given this information you can calculate what you need to know about your circle.