Answer:
x= 12.04
Explanation:
For this problem you would use the equation C^2-A^2=B^2. C would be the hypotenuse, aka 17 in this case. A would be the other known variable, aka 12. You square both of those and get 289-144=B^2. The answer to that is 145. As a final step you need to find the square root of 145, which is 12.04.