The Interactive Geometry Software Cinderella

Forum: Cinderella Support (E)

Forums->Cinderella Support (E)->basic arithmetic

1 stars
basic arithmetic

Thank you for writing this wonderful program!

I am using the free version of Cinderella 2. I was wondering if there was any way of performing basic arithmetical calculations on lengths and angles measured in a construction. Specifically, I am looking for a way to display the cross-ratio (BC:CD):(BE:ED) of four points BCDE on a line (see attached construction).


attachment Cross-ratio.cdy (5.21 Kb)
on: Fri 17 of Jun, 2011 [14:38 UTC] reads: 121080

Posted messages

author message
Aw: basic arithmetic
on: Fri 17 of Jun, 2011 [22:22 UTC]

yes, you can do that. Just press the f(x) button (you might have to enable the complete toolbar in the configuration menu) to add the formula


You can also create the distances |B,C| by dragging from B to C while entering the formula.

I attach the construction.

Hope that helps

PS: In your construction you move the crossing line by moving B and C — this makes it difficult to demonstrate the invariance of the cross ratio. I suggest you add two more points that are used for positioning the line and create "lines through point A" that won't move. I changed that for my example...

attachment Cross-ratio-new.cdy (4.27 Kb)

author message
1 stars
Re: Aw: basic arithmetic
on: Sat 18 of Jun, 2011 [14:22 UTC]
Very helpful. Thank you!


Show posts: