The missing side of the 90-degree triangle is 20.5 ft.
The Pythagorean Theorem states that in a right triangle, the square of the hypotenuse is equal to the sum of the squares of the other two sides. Therefore, we can use the following equation to find the missing side:
hypotenuse² = leg² + leg2²
Substituting the given values, we get:
hypotenuse² = 14.7² + 11.7²
hypotenuse² = 283.89 + 136.89
hypotenuse² = 420.78
Taking the square root of both sides, we get the hypotenuse:
hypotenuse = √420.78
hypotenuse = 20.5 ft
Therefore, the missing side of the 90-degree triangle is 20.5 ft.