What's the tool used to create geometry illustration graphics on wikipedia [closed]

Question

When I read articles about geometry/graphics on wikipedia, I see some very clean illustration graphics, for example:

Is there any way to create graphics like this easily?

[edit] I got 3 votes for close this topic when it was viewed 6 times. Ok, let me give more background here: I'm a programmer mainly for CAD tools. I need to check wikipedia when I have problems for some basic geometry calculation. So I read articles which includes some clean geometry illustration graphics.

I know that it's easy to create graphics like this in a CAD tool. But I don't think people will spend more than US$1000 to buy a CAD tool just in order to draw graphics like this.

Actually my favorite illustration tool is Microsoft PowerPoint. I used it a lot to help me analysis. It's really easy for me to quickly draw some illustrations like this. But today I got some issues. I want to draw 3 lines and make their length fixed, then drag the end points of them to verify my algorithm. The requirement is: when I drag the end points, the length of the 3 lines should be fixed, or in future I can adjust it accurately(I mean, with a specific number). I tried PowerPoint for a while, but cannot make it. Then I posted this question to stackoverflow, my favorite Q&A community. I also has some contributions to this community.

Why 50% of your guys viewed this question and vote for close?

Answer 1

I looked at the meta data for the creator's images

SVG comments indicate that they were created by Inkscape.

However, this may simply be the tool he used for final post-processing, not for creating the original images.