Answer:
x ≈ 13.42
Explanation:
Using Pythagoras' identity in the right triangle.
The square on the hypotenuse is equal to the sum of the squares on the other 2 sides, that is
x² + 12² = 18²
x² + 144 = 324 ( subtract 144 from both sides )
x² = 180 ( take the square root of both sides )
x =
≈ 13.42 ( to the nearest hundredth )