Answer:
11
Step-by-step explanation:
(next time, it would be helpful to include a picture)
If you were on the same test as I was, than that means that the triangle you're looking for is the one below.
Using the Pythagorean Theorem,
a² + b² = c² is the same as c² - b² = a²
c = 61
61^2 = 61 X 61 = 3,721
b = 60
60^2 = 60 X 60 = 3,600
Next, we subtract:
3,721 - 3,600 = 121
√121 = 11
(x = 11 cm)
so 11 is your answer