looks like u solved it

Couldn't you write the whole regex as ^(\d{1,3}\.){4}$

Ruby-Translation kumited!

https://www.codewars.com/kumite/58d471dfd929c8ed44000038?sel=58d471dfd929c8ed44000038

Could you check and approve it, please?

I like how you listed your plan for the function, I think a good deal of programmers lack that ability. The fact that you're using it on such a short kata shows you're building/maintaining a good habit. Nice.

Could you explain your regex? I get the first part, but whey do you do \d{1,3} a second time?

You're welcome!

I like your answer too, thank you for taking the time to explain that!

Ah, okay then. That was really well explained! I've known about a2 + b2 = c**2, and figured that c was the radius, but I was thinking about it the wrong way, in that (either) a or b should have been the radius. Makes more sense that way actually.

Thank you!

The best example that I have found in a few seconds.

http://www.samuellaboy.com/New_Folder/Special_Topics/My%20des3.gif

Draw a circle with the diameter line (= 2r), then draw a triangle with this line and use the formula learned at school

I'm horrible with math, can you explain why this works? (Or provide a weblink that can visually explain it?)