Let's fill in the blanks step by step.
We start with the Pythagorean theorem:
\[ a^2 + b^2 = c^2 \]
In this case, \( a \) is the distance from the wall (3 feet), and \( b \) is the height (13 feet). Therefore, we have:
\[ 3^2 + 13^2 = c^2 \]
Calculating \( 13^2 \):
\[ 13^2 = 169 \]
Now we can replace the blank in the equation with 169:
\[ 9 + 169 = c^2 \]
Now we add:
\[ 9 + 169 = 178 \]
So we have:
\[ c^2 = 178 \]
Now take the square root to find \( c \):
\[ c = \sqrt{178} \]
Using a calculator to compute:
\[ c \approx 13.34 \]
So we fill in the last blank:
c ~ 13.34 ft