Respuesta :

the problem is that 7^2 is 7*7, and the same for 8^2. The right answer is the square root of 15, or 3.87
He/she forgot that 8^2=64 not 16, and 7^2=49 not 14. As a result, the correct answer is:
a^2+b^2=c^2
7^2+b^2=8^2
49+b^2=64
b^2=15
b≈3.9 cm. Hope it help!