Can 2 Lines With Negative Slopes Be Perpendicular

The question of whether two lines with negative slopes can be perpendicular is a fascinating one in the world of geometry. It touches upon the fundamental relationships between lines and their orientations in a coordinate plane. Let’s dive deep to understand the core principles that govern this geometrical puzzle. Can 2 Lines With Negative Slopes Be Perpendicular? The answer might surprise you.

The Geometric Dance of Perpendicular Lines

In the realm of coordinate geometry, lines are defined by their slopes, which indicate their steepness and direction. A negative slope signifies that as you move from left to right along the line, you are moving downwards. Perpendicular lines, on the other hand, are lines that intersect at a perfect 90-degree angle. The key to understanding if two negative-sloped lines can be perpendicular lies in the relationship between their slopes.

For any two non-vertical lines to be perpendicular, the product of their slopes must equal -1. This is a fundamental rule in coordinate geometry. Let’s consider some scenarios:

  • If line 1 has a slope of -2, and line 2 has a slope of 1/2, their product is (-2) * (1/2) = -1. These lines are perpendicular.
  • If line 1 has a slope of -1/3, and line 2 has a slope of 3, their product is (-1/3) * (3) = -1. These lines are also perpendicular.

However, the question specifically asks about lines *with negative slopes*. This means we are looking for two lines where both slope1 < 0 and slope2 < 0. Let’s examine this using a table:

Line 1 Slope Line 2 Slope Product of Slopes Are they Perpendicular?
-2 -1/2 (-2) * (-1/2) = 1 No
-3 -1/3 (-3) * (-1/3) = 1 No
-5 -1/5 (-5) * (-1/5) = 1 No

As you can observe from the table, when you multiply two negative numbers, the result is always a positive number. The rule for perpendicular lines states that the product of their slopes must be -1. Therefore, it is impossible for two lines with negative slopes to be perpendicular to each other. At least one of the lines must have a positive slope for them to intersect at a right angle.

To further illustrate, consider the visual representation. A line with a negative slope descends from left to right. If you have two such lines, they will either intersect with an acute angle (less than 90 degrees) or an obtuse angle (greater than 90 degrees), but never a right angle. A right angle requires one line to be “going down” and the other to be “going up” relative to each other, which is precisely what a positive and a negative slope accomplish when their product is -1.

Now that you’ve explored the geometric principles behind this geometrical concept, feel free to refer back to the explanations and examples provided in this article for a thorough understanding.