15^2+8^2=c what is c?

it is 289, not 189, rarinstraw

You are talking about the Pythagorean Theorem, correct?

It should be $\sqrt{15^2+8^2}=c$

So $\sqrt{189}=c$

sqrt(189)=c = c=3*sqrt(21)

The answer is 17, btw.

$c=\sqrt{a^2+b^2}\Rightarrow c=\sqrt{15^2+8^2}\Rightarrow c=\sqrt{225+64}\Rightarrow c=\sqrt{289} \Rightarrow c=17$

The hypotenuse is 17