As for the circumference to find the diameter

Determining the diameter of a circle can be useful not only for solving geometric problems, but to help in practice. For example, knowing the diameter of the neck of the banks, you will not go wrong in choosing the cover for her. The same is also true for larger circles.

As for the circumference to find the diameter
How to calculate the circumference
How to measure the circumference
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Instruction

Suppose you want to buy a cover for the well, but the exact diameter is not known, but known components, only the circumference.

So, enter the names of the variables. Let d – diameter of the well, L is the circumference, n is the number PI, whose value is approximately equal to 3.14, R is the radius of the circle. The circumference (L) are known. Assume that it is equal to 628 cm.

Then to find the diameter (d) use the formula for the circumference of a circle: L=2PR, where R is the unknown variable, L=628 cm, and p=3,14. Now use the rule to find unknown multiplier: "to find an unknown multiplier, we need work divided by the known multiplier." Obtained: R=L/2P. The substitute values to the formula: R=628/2x3. 14. Obtained: R=628/6,28, R=100 cm.

After the radius of the circle was found (R=100 cm), use the following formula: the diameter of a circle (d) is equal to two radii of the circle (2R). Turns out: d=2R.

Now, to find the diameter, substitute into the formula d=2R values and calculate the result. Since the radius (R), is obtained: d=2x100, d=200 cm.

Is the advice useful?