The diameter can be measured. It is any line that passes through the centre of the circle and cuts the circle into two equal halves by touching the circle on either end.

The diameter is twice the radius. So, if the radius (r) is known, the diameter (d) is found by:

d = 2*r

The circumference of a circle is found by multiplying the diameter by pi (?). So if the circumference (c) is known, the diameter is:

d = c / ?

The area of a circle is found by multiplying pi by the square of the radius. If the area (a) of the circle is known, then the radius can be found by:

r = ?(a/?)

since d = 2*r,

d = 2?(a/?)

Given the radius of a circle is R, then the diameter of a circle can be calculated using the formula

Diameter = 2R

where R is the radius of a circle

OR

If you are given the that circumference of a circle is ( C ), then the diameter of a circle can be found using the formula

Diameter = ( C/pi )

where;

C = the circumference of a circle.

and Pi , approximately is 3.14

OR

If the area of a circle is ( A ), the diameter of a circle can be found using the formula

Diameter =? (4A/pi)

where A is the area of the circle

and Pi , approximately is 3.14

The diameter of a circle is the length of the line segment that passes through the center of the circle and touches two endpoints on its edge

Diameter= 2R

where R= Radius of the circle

OR

Diameter = ( C/pi )

where;

C = the circumference of a circle.

and Pi , approximately is 3.14

OR

(Diameter)^2 =(4A/pi)

where A is the area of the circle

and Pi , approximately is 3.14

1. Use ruler

2. Diameter D = 2*r , r = radius

3. D = C/pi where C is curcumference

4. D = 2*Sqrt(A/pi) where A is the area

5. Ask the circle very nicely :)

The diameter of a circle is the length of the line through the center and touching two points on its edge.

Also, if the radius, r is known, diameter is equal to 2*r.

Diameter of a circle = r *2(For example if the r = 5 then the diameter of the circle is 10)

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