Since the triangle is a right triangle, you can use the Pythagorean Theorem to find the length of the hypotenuse.
The Pythagorean Theorem: a² + b² = c², where c is the hypotenuse of the triangle.
Plug in the leg lengths and solve.
a² + b² = c²
3² + 4² = c²
9 + 16 = c²
25 = c²
5 = c
Answer:
The length of the hypotenuse is 5 ft.