Answer:
x = 6 sqrt(3)
Explanation:
Since this is a right triangle, we can use the Pythagorean theorem
a^2 + b^2 = c^2 where a and b are the legs and c is the hypotenuse
6^2+ x^2 = 12^2
36 + x^2 = 144
Subtract 36 from each side
x^2 = 144-36
x^2 =108
Take the square root of each side
sqrt(x^2) = sqrt(108)
x = sqrt(36*3)
x = 6 sqrt(3)