A ladder is leaning against a wall, forming a 45-degree angl...

Question Analysis
This problem assesses the application of the cosine function in a real-world context, specifically in a 45-45-90 triangle.

Key Concept Explanation
In a 45-45-90 triangle, the sides are in the ratio 1:1:√2. The cosine of 45 degrees is or .

Step-by-step Solution
1. Identify the given values: hypotenuse (ladder) = 28 feet, angle = 45 degrees.
2. Use the cosine of 45 degrees:
3. Set up the equation: