Question

1.) What is the equation of a vertical line passing through the point (2, -4)?

2.) What is the equation a horizontal line passing through the point (2, -4)?
3.) What is the two lines above relationship to each other?

Answer 1

The points lying on a vertical line share the same
`x` coordinate. Similarly, the points lying on a horizontal line share the same
`y` coordinate.

So, vertical lines are identified by the
`x` coordinate of their points, and have an equation like
`x=x_0`, where
`x_0` is a fixed real number.

Similarly, horizontal lines are identified by the
`y` coordinate of their points, and have an equation like
`y=y_0`, where
`y_0` is a fixed real number.

We are ready to answer the questions:

1. A vertical line passing through the point (2, -4) has equation
   `x=2`
2. A horizontal line passing through the point (2, -4) has equation
   `y=-4`
3. The two lines are perpendicular