To find the missing length $c$ in the right triangle, we can use the Pythagorean theorem. The Pythagorean theorem states that in a right triangle, the square of the length of the hypotenuse $c$ is equal to the sum of the squares of the lengths of the other two sides.

The formula is: $c^2 = a^2 + b^2$

In this triangle, $a = 9$ feet and $b = 12$ feet. We need to find $c$.

$c^2 = 9^2 + 12^2$ $c^2 = 81 + 144$ $c^2 = 225$ $c = \sqrt{225}$ $c = 15$

Therefore, the length of $c$ is 15 feet.

Would you like more details or have any questions?

Here are some related questions:

1. How do you calculate the hypotenuse in a right triangle if given different side lengths?
2. What are some practical applications of the Pythagorean theorem?
3. How can you verify if a triangle is a right triangle using side lengths?
4. What other methods can be used to find the length of a side in a right triangle?
5. Can the Pythagorean theorem be used for triangles that are not right triangles?
6. How does trigonometry relate to the Pythagorean theorem?
7. What are the implications of rounding in practical applications of the Pythagorean theorem?
8. How do you handle problems involving right triangles with non-integer side lengths?

Tip: When working with the Pythagorean theorem, always ensure the triangle is a right triangle before applying the formula.