Final answer:
Perpendicular lines have slopes that are negative reciprocals of each other, meaning if one line has a slope of 3, a line perpendicular to it would have a slope of -1/3.
Step-by-step explanation:
When two intersecting lines form a right angle, they are perpendicular to each other.
Perpendicular lines have slopes that are negative reciprocals of one another.
For example, if one line has a slope of 3, represented as a rise of 3 on the vertical axis for every increase of 1 on the horizontal axis, the slope of a line perpendicular to it would be -1/3. In other words, the product of the slopes of two perpendicular lines is -1.
This is derived from the concept that the slopes are inversely proportional and their product equals the slope of a right angle, which is defined as being 90 degrees and having a slope of undefined or infinite.