Two additional runways are planned. Each will pass through the point (0,-4) on the coordinate plane.

Runway B is to be parallel to runway A.

Runway C is to be perpendicular to runway A.

Which equations could describe either of those runways? Choose all that are correct.

A. y=-3/4x-4

B. y=4/3x-4

C. y=-4/3x-4

D. y=3/4x-4

1 answer

To find the equations for runways B and C based on the specifications given about their relationships with runway A, we need to analyze the slopes.

  1. Finding the slope of runway A:

    • The phrase "runway B is to be parallel to runway A" indicates that it will have the same slope as runway A.
    • The phrase "runway C is to be perpendicular to runway A" indicates that its slope will be the negative reciprocal of the slope of runway A.
  2. Analyzing the provided equations and finding their slopes:

    • A. \( y = -\frac{3}{4}x - 4 \) → Slope = \(-\frac{3}{4}\)
    • B. \( y = \frac{4}{3}x - 4 \) → Slope = \(\frac{4}{3}\) (negative reciprocal of \(-\frac{3}{4}\))
    • C. \( y = -\frac{4}{3}x - 4 \) → Slope = \(-\frac{4}{3}\)
    • D. \( y = \frac{3}{4}x - 4 \) → Slope = \(\frac{3}{4}\) (negative reciprocal of \(-\frac{4}{3}\))
  3. Determine which equations fit the criteria for either runway B (parallel) or runway C (perpendicular):

    • From equation A, if we take the slope \(-\frac{3}{4}\):

      • For runway B (parallel), we need to keep the slope \(-\frac{3}{4}\). Thus, equation A is a possibility.
      • For runway C (perpendicular), we would need a slope of \(\frac{4}{3}\), which corresponds to option B.
    • If using equation A's slope \(-\frac{4}{3}\):

      • For runway B (parallel), we would need a slope of \(-\frac{4}{3}\), which corresponds to option C.
      • For runway C (perpendicular), the slope would be \(\frac{3}{4}\), which corresponds to option D.
  4. Summary of the slopes:

    • If runway A has a slope of \(-\frac{3}{4}\), then:

      • Runway B can be represented by A (same slope: A).
      • Runway C can be represented by B (perpendicular: B).
    • If runway A has a slope of \(-\frac{4}{3}\), then:

      • Runway B can be represented by C (same slope: C).
      • Runway C can be represented by D (perpendicular: D).
  5. Conclusion: Therefore, the equations that could describe either runway B or C are:

  • A. \( y = -\frac{3}{4}x - 4 \) (can be runway A itself).
  • B. \( y = \frac{4}{3}x - 4 \) (perpendicular to A if A was with slope \(-\frac{3}{4}\)).
  • C. \( y = -\frac{4}{3}x - 4 \) (can serve as runway A with a slope of \(-\frac{4}{3}\)).
  • D. \( y = \frac{3}{4}x - 4 \) (perpendicular to A if A had slope \(-\frac{4}{3}\)).

Thus, the correct choices are:

  • A
  • B
  • C
  • D

All options can describe either runway B or C depending on the slope of runway A being considered.