Answer:
2√11
Explanation:
The square of the hypotenuse (h) of the smaller triangle is given by the Pythagorean theorem:
h² = 6² +8² = 100
The length of x is given by that same theorem:
h² +x² = 12²
x² = 12² -h² = 144 -100 = 44 . . . . . subtract h², fill in its value
x = √44 . . . . . . . . take the square root
x = 2√11 . . . . . . . simplify the root