Answer:
b=-784!
Step-by-step explanation:
If pythagorean theorem is the following (see below), then we can work backwards in order to solve for b!
[tex]a^{2} +b^2=c^2[/tex]
[tex]35^2 +b=21^2\\1225+b=441[/tex]
Now all that's left is to subtract 1225 and we should have our answer!
[tex]b=-784![/tex]
