How to calculate Circumference, Diameter, Area, and also Radius

The circle calculator find the area, radius, diameter and also circumference that a circle labeled as a, r, d and c respectively.

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For those having an obstacle using formulas manually to uncover the area, circumference, radius and diameter that a circle, this one calculator is just for you. The equations will be given below so you have the right to see exactly how the calculator obtains the values, yet all you need to do is intake the straightforward information. The calculator does the rest.


Finding the Circumference:

The one is similar to the perimeter in that it is the total length necessary to draw the circle.

We note the circumference as c.

c = 2πr


c = πd

This counts on even if it is or no you understand the radius (r) or the diameter (d)

Let’s calculation one manually, for example.

If r = 6 cm, the the circumference is c = 2π(6) = 12π cm, if composing in regards to π. If you prefer a number value, the answer rounded to the nearest tenth is 37.7 cm.

Suppose girlfriend only know the diameter? If the diameter is 8 cm, climate the one is c = π(8) = 8π or 25.1 cm, rounded come the nearest tenth.

A great thing about the recipe is that you can manipulate the to fix for an unknown if you know one of the other quantities. Because that example, if we understand the circumference, but don’t understand the radius, you deserve to solve c = 2πr for r and also get \(r = \fracc2\pi\). Similiarly, if you want the diameter indigenous the circumference, simply take c =πd and also solve for d to acquire d = \(\fracc\pi\).


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Finding the Area:

Let a = area of the circle

a = πr²

If you know the diameter and also not the radius, merely divide the diameter by 2 to obtain the radius and also still usage the formula above.

Again, the formula deserve to be offered to solve for the radius, if you know the area. Just divide a by π to obtain r² and take the square source of the result.

If you great to understand the diameter native the area, monitor the procedure above but double the an outcome you obtain for r. This is since the diameter is twice the length of the radius.

Try an example manually to get the area.

Suppose r = 5 inches

a = πr²

a = π(25) = 25π

If rounding to the nearest tenth the area is 78.5 square inches.

If you understand the diameter, just divide by 2 to acquire the radius and use the same formula as above.

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Of course, you don’t need to go with all the hands-on calculations to use this calculator. Just input the information you know and also the rest will be computed because that you practically instantly.