To find the unknown side length of the right triangle using the Pythagorean Theorem, we can apply the formula:
\[ a^2 + b^2 = c^2 \]
where:
- \( a \) is one leg (base), which is 3,
- \( b \) is the other leg (the unknown side),
- \( c \) is the hypotenuse, which is 15.
Substituting the known values, the equation becomes:
\[ 3^2 + b^2 = 15^2 \]
Calculating the squares:
\[ 9 + b^2 = 225 \]
Now, to solve for \( b^2 \):
\[ b^2 = 225 - 9 \] \[ b^2 = 216 \]
Next, we take the square root of both sides to find \( b \):
\[ b = \sqrt{216} \] \[ b \approx 14.7 \]
So, rounding to the nearest tenth, the unknown side length is approximately 14.7.
The correct response is:
14.7