# Area of an elliptical sector Calculator

## Calculates the area and arc of an elliptical sector given two axes and two angles. | ||

[1-3] /3 | Disp-Num |

- Purpose of use
- To help me calculate the Hydraulic radius for Elliptical pipes when not in full flow.
- Comment/Request
- Still getting my head round the arguments put forward, In order to make better use of them at the moment

- Bug report
- Hi there,

When I compare the results of these formula to another derivation (http://math.stackexchange.com/questions/114371/deriving-the-area-of-a-sector-of-an-ellipse) I find that inputs of

angle theta0 = -0.6 (rad)

angle theta1 = 0.8

semimajor axis a = 1100

semiminor axis b = 979

give different results. Your calculator returns 814,874.12267598 and the formula (a*b/2)(atan((a/b)*tan(theta1))-atan((a/b)*tan(theta0))) returns 753830.0.

Which one is wrong? Is it possible for you to post a derivation of your formulas? - from Keisan
- Please refer to "The Area of Intersecting Ellipses (David Eberly)" on Related links.

- Purpose of use
- I'm trying to calculate how much of the area of an ellipse I will block if I install a deflector plate across part of the opening. In addition to the information you provide, I need to know the chord length across L. I was looking for website that would do it, but it looks like I will have to do some real math myself.

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