Your correct answer should be choice D
Cos(arcsin(u)) = √(1 - u²)
_____
You want cos(α) where sin(α) = u.
You know that
cos(α)² + sin(α)² = 1
cos(α)² = 1 - sin(α)² = 1 - u²
cos(α) = √(1 - u²)
The answer would be B
What you would do is 180-72= 108 degrees
The area of the entire surface will be 2160 feet Wide/Long.
