27? i cant figure out her mistake can anyone ?

The mess up occurs in one of the first things she says. She first claims that 7^2 +25^2 = 24^2
Wait a minute... slow your roll there.
25 is the hypotenuse, or the longest side of the triangle AND opposite the right angle (but we aren't supposed to know that yet).
The Pythagorean Theorem holds that a^2 + b^2 = c^2, where a & b are the legs of the triangle & c is the hypotenuse. So, she got the formatting correctly, but she switched 24 & 25.
Hope this helps!

The mistake is she uses 7² + 25² = 24² when the actual equation should be 7² + 24² = 25² which would be correct 7² = 49 / 24² = 576 / 49 + 576 = 625 which is equal to 25²