# How to calculate the diameter of the circle?

For starters, let's see what the circle and how does it differ from a circle.Take a pen or pencil and draw a red sheet of paper on a regular cycle.Paint the entire mid resulting figure in blue pencil.The red outline marks the boundary shapes - a circle.But the contents of the blue inside - and there's a circle.

size of the circle and circle diameter are determined.The red curve indicating circle mark two points so that they were mirror images of each other.Connect them to the line.The length required to pass through a point at the center of the circle.This segment connecting the opposite part of the circumference and the diameter is called geometry.

segment that runs through the center of the circle is not, but it merges with the opposite ends is called a chord.Consequently, the chord runs through the center point of a circle and its diameter is.

denotes the diameter of the Latin letter D. Finding the diameter of the circle may be on such values ​​as area, length and radius of the circle.

distance from the center point to the point of choice on the circle is called the radius and denoted by the letter R. Knowing the radius helps calculate the diameter of the circle with one simple action:

D = 2 * R

For example, the radius - 7 cm. Multiply 7cm 2, and get a value equal to 14 cm. Answer: D given figure is 14 cm.

Sometimes you have to determine the diameter of the circle only on its length.Here it is necessary to use a special formula to help determine the length of the circumference.Formula L = 2 pi * R, where 2 - is a constant quantity (constant), and P = 3.14.And since we know that R = D * 2, the formula can be expressed in another way

L = Pi * D

D = L / P

This expression applies the formula diameter circle.Substituting the known values ​​of the problem, solve the equation with one unknown.For example, the length is 7 m. Hence:

D = 7/3, 14

D = 21, 98

Answer: The diameter is 21.98 meters.

If you know the value of the area, it is also possible to determine the diameter of the circle.The formula which is used in this case is as follows:

D = 2 * (S / P) * (1/2)

S - in this case square shape.For example, in the problem, it is 30 square meters.m. We obtain:

D = 2 * (30/3, 14) * (1/2) D = 9, 55414

When designated in the problem size, equal to the volume (V) of the ball, the following formula is finding diameter: D= (6 V / P) * 1 / 3.

Sometimes you have to find the diameter of a circle inscribed in a triangle.To do this, find the radius represented by the formula circumference:

R = S / p (S - a predetermined area of ​​the triangle, and p - the perimeter divided by two).

The result is doubled, given that D = 2 * R.

often have to find the diameter of a circle and at home.For example, when determining the size of the ring, which is equivalent to its diameter.To do this, wrap the potential owner of the ring finger thread.Mark the point of contact between the two ends.Measure the length of the line from point to point.The resulting value is multiplied by 3.14, following the formula for determining the diameter at a known length.So the assertion that knowledge of geometry and algebra in life is not useful, do not always correspond to reality.This is a serious cause for concern more responsibly to school subjects.

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