Is it possible to split all straight lines in a plane into the pairs of perpendicular lines, so that every line belongs to a single pair?
Solution
1. Set up an x-y coordinate system: Consider a Cartesian coordinate system where each line can be represented by an equation in the form or .
2. Identify perpendicular lines: Two lines are perpendicular if the product of their slopes is . For example, if one line has a slope , the perpendicular line will have a slope .
3. Consider lines parallel to the x- and y-axes: Lines parallel to the x-axis have the form (horizontal lines), and lines parallel to the y-axis have the form (vertical lines). These lines are always perpendicular to each other.
4. Pairing horizontal and vertical lines: For any given point , the horizontal line through this point is and the vertical line through this point is . These two lines are perpendicular and can be paired together.
5. Generalization: The argument can be extended to any point in the plane. The horizontal line through this point is and the vertical line through this point is . These lines are also perpendicular and can be paired together.
6. Conclusion: Since every line parallel to the x-axis can be paired with a line parallel to the y-axis through some point , it is possible to pair all such lines into perpendicular pairs.
However, this argument only covers lines parallel to the x- and y-axes. For lines with arbitrary slopes, the problem becomes more complex. Consider lines with slopes and such that . There is no guarantee that every line can be paired with another line to satisfy this condition, as the number of lines with a specific slope is not necessarily equal to the number of lines with the negative reciprocal slope.
Therefore, it is not possible to pair all straight lines in a plane into pairs of perpendicular lines such that every line belongs to a single pair.
The final answer is False.