Based on the situation above, it forms into a right triangle. Therefore we can apply the Pythagorean Theorem. We will use the formula below:
c = √( a² + b²)
In the problem above, the ladder acts as the hypotenuse denoted by c. It has a length of 20 ft. While the base denoted by b is 12 ft. Therefore, we need to solve for a. We will derive the formula above.