Kepler's 2nd. Law

[Ángel Martin]

(02-13-2018 01:07 AM)toml_12953 Wrote:  

(02-12-2018 09:53 AM)Ángel Martin Wrote:  Example: calculate the area swept between a1 = pi/4 and a2 = 3.pi/4, if the ellipse parameters are a= 2, b= 3

Solution: A = 1.989554087

For the parameters a=2, b=3 and a1=.785398..., a2=2.35619...

(Did I get the parameters right?)

I get 5.89676233948396 which agrees with the calculator at

http://keisan.casio.com/exec/system/1343722259

Mmm... something's fishy. I consistently get 1.989554087 using a1 = pi/4 (45 degrees) and a2 = 3.pi/4 (135 degrees).
Besides, it's not possible to get the same as the web applet - which uses centered sectors, not focus-centered ones.

In fact, using the angles above the applet shows an Area result of 3.5280156212854

Could you double check?