Calculate Circle Radius/Diameter from Surface Area

In summary, to find the diameter of a circle given its area, you can use the formula d = 2r, where r is the square root of the area divided by pi. For example, if the area is 5.26 mm2, the radius would be √(5.26/π) ≈ 1.29 mm and the diameter would be 2(1.29) = 2.58 mm.
  • #1
magmash
18
0
Hi

How is circular surface area values square rooted ??. I am using this formula r2Xπ=mm2 to calculate the surface area of a circle but i want to know if there is a formula to get back to the diameter or the radius of the circle ?.

example i have a circular surface area of 5.26mm2 and i want the diameter of that value, how do i solve this ?

Thanks in advance
 
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  • #2
[itex] S=\pi r^2 \Rightarrow r^2=\frac{S}{\pi} \Rightarrow r=\sqrt{\frac{S}{\pi}} [/itex]
 
  • #3
Shyan said:
[itex] S=\pi r^2 \Rightarrow r^2=\frac{S}{\pi} \Rightarrow r=\sqrt{\frac{S}{\pi}} [/itex]
Thanks for the replay Shyan.

a circel with a diameter of 1.29mm 0.6452π = 1.30 The formula you mentioned √s/π gives a value of 0.362.. ?

Could you show me an example, I would be very thanks full
 
  • #4
magmash said:
Thanks for the replay Shyan.

a circel with a diameter of 1.29mm 0.6452π = 1.30 The formula you mentioned √s/π gives a value of 0.362.. ?

Could you show me an example, I would be very thanks full
Careful boy! Its not [itex] r=\frac{\sqrt{S}}{\pi} [/itex], its [itex] r=\sqrt{\frac{S}{\pi}} [/itex].
 
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Likes magmash
  • #5
:DThanks
 
  • #6
magmash said:
Hi

How is circular surface area values square rooted ??.
We don't call it "surface area" - just area. Surface area applies to surfaces in three dimensions. For objects in the plane (two dimensions), we talk about the area.
magmash said:
I am using this formula r2Xπ=mm2
The actual formula is ##A = \pi r^2##. If r is given in mm., then the units of area will be square millimeters or mm2. The formula shouldn't explicitly show units.
magmash said:
to calculate the surface area of a circle but i want to know if there is a formula to get back to the diameter or the radius of the circle ?.
From the equation ##A = \pi r^2##, to get the radius, solve for r. To do this, divide both sides of the equation by ##\pi##, then take the square root. Once you have the radius r, you can get the diameter using d = 2r.
magmash said:
example i have a circular surface area of 5.26mm2 and i want the diameter of that value, how do i solve this ?

Thanks in advance
 

1. How do I calculate the radius of a circle from its surface area?

To calculate the radius of a circle from its surface area, you can use the formula: radius = √(surface area/π). This formula is derived from the equation for the surface area of a circle, which is surface area = π * radius^2. By rearranging the equation, we can solve for the radius using the given surface area.

2. Is there a different formula for calculating the diameter of a circle from its surface area?

Yes, there is a different formula for calculating the diameter of a circle from its surface area. The formula is: diameter = 2 * √(surface area/π). This formula is derived from the formula for the circumference of a circle, which is circumference = 2 * π * radius. By substituting the formula for radius from the previous question, we can calculate the diameter using the given surface area.

3. Can I use the same formula to calculate the radius or diameter from any given surface area?

Yes, the formula radius = √(surface area/π) and diameter = 2 * √(surface area/π) can be used to calculate the radius or diameter from any given surface area. However, it is important to remember to use the appropriate units for the surface area (e.g. square inches, square meters) and to use the same units for the radius or diameter.

4. What is the value of π to use in these calculations?

The value of π, or pi, that is commonly used in these calculations is 3.14159. However, for more precise calculations, you can use a more accurate value such as 3.14159265358979. Depending on the level of accuracy required for your calculations, you can use the appropriate number of decimal places for π.

5. Are there any other methods for calculating the radius or diameter from a given surface area?

Yes, there are other methods for calculating the radius or diameter from a given surface area, such as using a calculator or using a graphing software. These methods may be more efficient for larger or more complex calculations. Additionally, there are also online tools and apps that can perform these calculations for you.

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