If the circumference for a circle or ellipse is known, then the area can be calculated.
NOTE: This can be used to estimate the area of a cardiac valve from its circumference.
For a circle:
circumference of a circle =
= π * (diameter) =
= π * 2 * (radius)
area of a circle =
= ((circumference)^2) / (4 * π)
For an ellipse, one of the 2 axial diameters must also be specified.
circumference of an ellipse =
= 2 * π * SQRT(((((diameter 1) / 2)^2) + (((diameter 2) / 2)^2)) / 2)
diameter 2 =
= SQRT((2 * ((circumference)^2) / (π^2)) – ((diameter 1)^2))
area of ellipse =
= π * ((diameter 1) / 2) * ((diameter 2) / 2)
