On a coordinate plane, 2 lines are shown. Line C D has points (negative 2, 4) and (0, negative 4). Line F G has points (negative 4, 0) and (4, 2).

Which statement best explains the relationship between lines CD and FG?

They are perpendicular because their slopes are equal.
They are perpendicular because their slopes are negative reciprocals.
They are not perpendicular because their slopes are equal.
They are not perpendicular because their slopes are negative reciprocals.

1 answer

To determine the relationship between the lines CD and FG, we need to find the slopes of both lines and compare them.

Finding the slope of line CD: The points on line CD are (-2, 4) and (0, -4).

The formula for the slope (m) between two points \((x_1, y_1)\) and \((x_2, y_2)\) is:

\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]

Substituting the coordinates for line CD:

\[ m_{CD} = \frac{-4 - 4}{0 - (-2)} = \frac{-8}{2} = -4 \]

Finding the slope of line FG: The points on line FG are (-4, 0) and (4, 2).

Using the slope formula again:

\[ m_{FG} = \frac{2 - 0}{4 - (-4)} = \frac{2}{4 + 4} = \frac{2}{8} = \frac{1}{4} \]

Comparing the slopes:

  • The slope of line CD \(m_{CD} = -4\)
  • The slope of line FG \(m_{FG} = \frac{1}{4}\)

Now, we check if they are negative reciprocals:

To be negative reciprocals, the product of the two slopes should equal -1:

\[ m_{CD} \cdot m_{FG} = (-4) \cdot \left(\frac{1}{4}\right) = -1 \]

Since the product of the slopes is -1, this means the two lines are indeed perpendicular.

Thus, the correct statement is:

They are perpendicular because their slopes are negative reciprocals.