Sheridan's work is correct because the triangle shows only one leg and the hypotenuse. Since a^2 + b^2 = c^2, The hypotenuse (13) would go where c^2 is that means a^2 (7) and b^2 are the legs, we are only looking for the length of one of the legs. He solved from there and came out with the correct answer 10.95
No, they are both incorrect by my understanding of your question use the Pythagorean theorem a^2 + b^2 =c^, therefore, 7^2 +x^2 = 13^2 or 49+x=169 then solve normally 169-49=120 √120 =5
