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Jul 24, 2024 · The radius of a circle calculator returns the length of a circle's radius based on the input data: the circumference, area, or diameter.
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Write down the circumference formula. The formula is C = 2 π r {\displaystyle C=2\pi r} , where C {\displaystyle C} equals the circle’s circumference, and r {\displaystyle r} equals its radii.[2] X Research source The symbol π {\displaystyle \pi } ("pi") is a special number, roughly equal to 3.14. You can either use that estimate (3.14) in calculations, or use the π {\displaystyle \pi ...Solve for r. Use algebra to change the circumference formula until r (radius) is alone on one side of the equation:[3] X Research source Example C = 2 π r {\displaystyle C=2\pi r} C 2 π = 2 π r 2 π {\displaystyle {\frac {C}{2\pi }}={\frac {2\pi r}{2\pi }}} C 2 π = r {\displaystyle {\frac {C}{2\pi }}=r} r = C 2 π {\displaystyle r={\frac {C}{2\pi }}}Plug the circumference into the formula. Whenever a math problem tells you the circumference C of a circle, you can use this equation to find the radius r. Replace C in the equation with the circumference of the circle in your problem:[4] X Research source Example If the circumference is 15 centimeters, your formula will look like this: r = 15 2 π {\displaystyle r={\frac {15}{2\pi }}} centimetersRound to a decimal answer. Enter your result in a calculator with the π {\displaystyle \pi } button and round the result. If you don't have a calculator, calculate it by hand, using 3.14 as a close estimate for π {\displaystyle \pi } .[5] X Research source Example r = 15 2 π = {\displaystyle r={\frac {15}{2\pi }}=} about 7.5 2 ∗ 3.14 = {\displaystyle {\frac {7.5}{2*3.14}}=} approximately ...The number π {\displaystyle \pi } actually comes from circles. If you measure the circumference C and diameter d of a circle very precisely, then calculate C ÷ d {\displaystyle C\div d} , you always get π {\displaystyle \pi } . Thanks Helpful 1 Not Helpful 0If you have a given point and the coordinates of the center, you can use the distance formula to find the radius.- 3.6M
Aug 3, 2023 · How to Find the Radius of a Circle from the Area. When the area of the circle is known, the equation to get the radius is derived below. As we know, Area (A) = πr2, here r = radius, and π = 3.141 = 22/7. r2 = A / π. r = √A/π. Let us solve an example to illustrate the concept better.
Use our calculator to calculate the radius of a circle given a diameter, circumference, or area. See the formulas used to find the radius.
Learn how to find the radius of a circle using the formulas based on diameter, circumference, and area. See the definition, examples, and diagrams of radius and related concepts such as diameter, circumference, and equation of a circle.
What Is the Radius of a Circle? The radius of a circle represents the distance between the center and the boundary of the circle (circumference). The radius is generally denoted by “R” or “r.” The word “radius” is the singular form, while “radii” is the plural form.
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Calculate the radius, diameter, circumference, or area of a circle, and learn the formulas to find each property of a circle.
