Question

Two lines are perpendicular, and neither line is horizontal. Which of the following is not necessarily true of the lines?

A.
The slopes of the two lines are opposite reciprocals.
B.
One line must have a positive slope.
C.
The y-intercepts are the same.
D.
One line must have a negative slope.

Answer 1

I think the correct answer from the choices listed above is option C. Two lines are perpendicular, and neither line is horizontal so it must be that the slopes of the lines are opposite reciprocals, one slope is positive and the other has a negative slope. Having different slopes so they should intersect the y-axis at different values.