Wow: How to calculate an oval's area?
An oval is not a specific mathematical shape - it doesn't have very specific properies.
An ellipse looks like an oval but it has very defined feature. I'm going to talk about an ellipse.
If you wanted to draw a big circle in the yard (for a garden) one way to do it would be to put a post where you want the centre to be.
Have a piece of string that is as long as the diameter with a loop at each end
put both loops over the centre pole so the string is complely doubled over.
Stretch the rope out so it is taut, put some talcum powder in the loop at the end.
Walk around the pole allowing the powder to fall to the ground.
The fallen powder will make a circle.
Does that make sense?
If you want to make an ellipse, you need two poles. One end of the string gets looped over one pole, the other end gets looped over the other pole.
Then you use the powder and walk around exactly the same way. You end up with an ellipse. Kind of like a circle with 2 centres (1 focus, 2 foci ). It looks like a flattened circle.
140104 drawing an elipse.JPG
The ellipse has a major axis, this is the long axis of symmetry and a minor axis which is the short axis of symmetry.
On the picture below, A is the semi-major axis and B is the semi-minor axis.
The AREA of the ellipse is pi * A * B 140104 ellipse.JPG
http://www.math.hmc.edu/funfacts/ffiles/10006.3.shtml
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