<![CDATA[Ellipse construction]]>
https://help.geogebra.org/topic/ellipse-construction_1
Mon, 18 May 2020 17:34:05 +0000Tue, 12 May 2020 21:37:48 +0000Zend_Feed<![CDATA[This specification implies that there can be undefined states. given: A and B on major/minor axis and on ellipseC on ellipse and NOT on major/minor axis and the angles BAC/CAB and CBA/ABC < 90° (see alternative condition ("inside") in attachment ) Construction ellipse with 5 points Conic(A, B, C, Reflect(C, Line(A, B)), Reflect(C, PerpendicularBisector(A, B)))]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282050
Wed, 13 May 2020 01:42:21 +0000<![CDATA[Alternative (without undefined states, but in rare cases one of the 3 points is shift with 0.001 (this is less than 1 pixel) in x and y direction. See object C'')]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282054
Wed, 13 May 2020 03:00:25 +0000<![CDATA[Thank you for the answer, but for some reason this does not work on certain conditions. For example check this: https://www.geogebra.org/cl... This works well if Point F is free-floating. But then try to set F as Point(g) The ellipse will suddenly disappear. Is there any way to fix this?]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282160
Wed, 13 May 2020 15:51:20 +0000<![CDATA[Sorry, in this moment (and with the 5 point approach) I see no possibility for a 100% solution. But try Version 3 (with approximation), this works maybe better.]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282162
Wed, 13 May 2020 16:19:05 +0000<![CDATA[I see, that's a shame. Maybe it's possible with a different approach?]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282166
Wed, 13 May 2020 16:15:07 +0000<![CDATA[Maybe the approach from Patrick Clement is useful for you.]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282192
Thu, 14 May 2020 01:55:39 +0000<![CDATA[I tried it, but the problem is the third point isn't free. Also I just noticed your edit with Version 3, I didn't see it somehow. It seems the problem with the initial version is that if the third point is along a line perpendicular to the centre of the line between point 1 and point 2, the ellipse becomes undefined. But Version 3 seems to fix this problem But what do you mean by 'approximation'?]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282194
Thu, 14 May 2020 02:16:57 +0000<![CDATA[aproximativ: The drawn ellipse does not pass exactly through point C but through point C''. This point is (if necessary) shifted very, very little (much smaller than 1 pixel when standard zoom) in the right angle to direction of the half-axes. Thus, all values derived from the ellipse (area, perimeter etc) are not entirely accurate but aproximative (small fake but more useful than correctly nothing)]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282196
Thu, 14 May 2020 03:14:45 +0000<![CDATA[after a lot of informatic problems, PC crashed, I got it]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282454
Sat, 16 May 2020 10:57:50 +0000<![CDATA[Thank you for your effort. But it seems this method also doesn't work very well when the free point is along the path of the ellipse's minor axis.]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282620
Mon, 18 May 2020 16:16:48 +0000<![CDATA[para los casos particulares basta usar un if() y seleccionar un punto adecuado]]>
https://help.geogebra.org/topic/ellipse-construction_1#comment-282626
Mon, 18 May 2020 17:34:05 +0000