To solve for the height that the ladder reaches on the house using the Pythagorean Theorem, we'll denote:
- The length of the ladder (\(c\)) as 12 ft,
- The distance from the base of the house to the bottom of the ladder (\(a\)) as 6 ft,
- The height that the ladder reaches on the house (\(b\)) as the unknown we need to calculate.
According to the Pythagorean Theorem:
\[ a^2 + b^2 = c^2 \]
Substituting the known values:
\[ 6^2 + b^2 = 12^2 \]
Calculating the squares:
\[ 36 + b^2 = 144 \]
Now, subtract 36 from both sides to isolate \(b^2\):
\[ b^2 = 144 - 36 \]
\[ b^2 = 108 \]
Next, take the square root of both sides to find \(b\):
\[ b = \sqrt{108} \]
We can simplify \(\sqrt{108}\):
\[ \sqrt{108} = \sqrt{36 \cdot 3} = \sqrt{36} \cdot \sqrt{3} = 6\sqrt{3} \]
Now, using a calculator, we find \(6\sqrt{3}\):
\[ 6\sqrt{3} \approx 6 \cdot 1.732 \approx 10.392 \]
Rounding to the nearest tenth, the height that the ladder will reach is approximately:
\[ \boxed{10.4} \text{ ft} \]