Answer:
x ≈ 12.7
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 + x² = 18²
2x² = 324 ( divide both sides by 2 )
x² = 162 ( take the square root of both sides )
x =
≈ 12.7 ( to 1 dec. place )