MY ANSWER: Obtuse, because to find if the triangle is right, acute or obtuse you use the Pythagorean Theorem. You plug in the two smaller numbers in the equation to it looks like this, 7^2+10^2=12.2. Since the hypotenuse given in the problem is larger than the hypotenuse you get in the theorem it is obtuse.
Can someone explain what I did wrong?
The only thing I see wrong is ytour math:
\(7^2+10^2=12.2\) is not true.
\(7^2+10^2=149\) is true and \(15^2=225\) is true and \(\sqrt{7^2+10^2}\approx12.2\) is true.
If that is the exact answer you submitted, yes, that is why it would be marked wrong. you did not actually apply the Pythagorean Theorem in that equation. You came close, but forgot the root sign!