The bottom of a ladder must be placed 5 ft. from a wall. The ladder is 12 feet long.

Based on the diagram, what is the distance in feet from the ground that the ladder reaches the wall? Round to the nearest tenth.

1 answer

To find the height at which the ladder reaches the wall, we can use the Pythagorean theorem. Let's denote the following:

  • The length of the ladder \( L = 12 \) feet (this is the hypotenuse).
  • The distance from the wall \( d = 5 \) feet (this is one leg of the right triangle).
  • The height of the ladder on the wall \( h \) (this is the other leg of the right triangle, which we want to find).

According to the Pythagorean theorem:

\[ L^2 = d^2 + h^2 \]

Substituting the known values:

\[ 12^2 = 5^2 + h^2 \]

Calculating the squares:

\[ 144 = 25 + h^2 \]

Now, isolate \( h^2 \):

\[ h^2 = 144 - 25 \] \[ h^2 = 119 \]

Now, take the square root to find \( h \):

\[ h = \sqrt{119} \]

Calculating \( \sqrt{119} \):

\[ h \approx 10.9087 \]

Rounding to the nearest tenth, we find:

\[ h \approx 10.9 \text{ feet} \]

Thus, the distance from the ground that the ladder reaches the wall is approximately 10.9 feet.