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Units Significant Figures Answer: circumference C = 75.3982237 in In Terms of Pi π circumference C = 24 π in Solutions \[ \textbf{diameter} \, d = 2r \]\[d = 2 \times 12 \]\[d = 24 \] \[ \textbf{circumference} \, C = 2 \pi r \]\[C = 2 \times \pi \times 12 \]\[C = 24 \pi \]\[C = 75.3982237 \] \[ \textbf{area} \, A = \pi r^2 \]\[A = \pi \times 12^2 \]\[A = 144 \pi \]\[A = 452.389342 \] Share
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r = radius d = diameter C = circumference A = area π = pi = 3.1415926535898 √ = square root Calculator UseUse this circle calculator to find the area, circumference, radius or diameter of a circle. Given any one variable A, C, r or d of a circle you can calculate the other three unknowns. Units: Note that units of length are shown for convenience. They do not affect the calculations. The units are in place to give an indication of the order of the results such as ft, ft2 or ft3. Any other base unit can be substituted. Circle Formulas in terms of Pi π, radius r, and diameter d
Circle Calculations:Using the formulas above and additional formulas you can calculate properties of a given circle for any given variable. Calculate A, C and d | Given r \[A = \pi r^2 \] \[C = 2 \pi r \] \[d = 2r \] Calculate r, C and d | Given A \[r = \sqrt{\frac{A}{\pi}} \] \[C = 2 \pi r = 2 \pi \sqrt{\frac{A}{\pi}} \] \[ d = 2r = 2 \sqrt{\frac{A}{\pi}} \] Calculate A, r and d | Given C \[r = \frac{C}{2 \pi} \] \[A = \pi r^2 = \pi \left(\frac{C}{2 \pi}\right)^2 = \frac{\pi C^2}{4 \pi^2} = \frac{C^2}{4 \pi} \] \[d = 2r = \frac{2C}{2 \pi} = \frac{C}{\pi} \] Calculate A, C and r | Given d \[r = \frac{d}{2} \] \[A = \pi r^2 = \pi \left(\frac{d}{2}\right)^2 = \frac{\pi d^2}{4} \] \[C = 2 \pi r = 2 \pi \frac{d}{2} = \pi d \] Follow CalculatorSoup:
Radius Of A CircleThe radius of a circle is a line segment with one end at the center of the circle, and the other end on the circle itself. The radius is identified with a lower-case, italic r. Table Of Contents[hide][show]
Radius Of A Circle FormulaThe formula you use depends on what is known about the circle. Below are three different formulas you can use to find the radius, r, of a circle. Radius Formulas
The relationship between radius and diameter is an important one to know when learning to how to calculate the radius. Since the radius is a line segment from the center to the circle, and the diameter, d, is a line segment from on side of a circle through the center of a circle and out to the other side of the circle, it follows that a radius is 12 a diameter. How To Find The Radius Of A CircleTo find the radius of a circle, plug the given information into the correct formula. You can find the radius of any circle if you are given the circumference, area, or diameter. How To Find Radius From CircumferenceNo matter the size of the circle, the relationship of the radius to the circumference, C, is a constant, giving us the formula to find radius from circumference: You can also calculate the circumference of a circle with a given radius by using algebra to isolate the C in our formula. The radius to circumference formula is: C = 2πr Radius Of Circle From AreaYou can use the area to find the radius and the radius to find the area of a circle. The area of a circle is the space it occupies, measured in square units. Given the area, A, of a circle, its radius is the square root of the area divided by pi: The formula for radius to area is: A = πr2 How To Find Radius From DiameterIf you know the diameter of a circle, you can find its radius by dividing the diameter by 2: This is the simplest formula you can use to get the radius. If you need to go from radius to diameter, multiply radius times 2: d = 2r Radius Of A Circle Example
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Next Lesson:Area Of A Circle How do you find the radius when given the circumference?To find the radius from the circumference of a circle, you have to do the following:. Divide the circumference by π, or 3.14 for an estimation. The result is the circle's diameter.. Divide the diameter by 2.. There you go, you found the circle's radius.. |