I’m guessing you are asking this question because you want all three fields to be input/output, rather than just two fields for input and one for output.
Although it’s janky, it’s possible if you really want to use Coda. You can check out my post on getting that to work in Coda.
Especially see the last table “Events” where you can update Start, End, OR Duration to calculate the other two automatically. (Similar to the hypotenuse calculator you shared.)
As for embedding, Coda has a great help article on that.