Slope Theorems

Question 0

If the slopes of two nonvertical lines are equal,

Answer 0

then the lines are parallel.

Question 1

If two nonvertical lines are parallel,

Answer 1

then their slopes are equal.

Question 2

If two lines are perpendicular and neither is vertical,

Answer 2

then each line’s slope is the opposite reciprocal of the other’s.

Question 3

If a line’s slope is the opposite reciprocal of another line’s slope,

Answer 3

then the two lines are perpendicular.