Elementary Algebra

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Perpendicular Lines

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Elementary Algebra

Definition

Perpendicular lines are a pair of lines that intersect at right angles, forming a 90-degree angle. They are an essential concept in understanding the slope of a line, as perpendicular lines have a unique relationship with their slopes.

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5 Must Know Facts For Your Next Test

  1. The slopes of perpendicular lines are negative reciprocals of each other, meaning if the slope of one line is $m$, the slope of the perpendicular line is $-1/m$.
  2. Perpendicular lines can be used to find the equation of a line that is perpendicular to a given line and passes through a specific point.
  3. The product of the slopes of two perpendicular lines is always equal to -1.
  4. Perpendicular lines can be used to construct geometric shapes, such as squares and rectangles, where all angles are 90 degrees.
  5. Identifying perpendicular lines is crucial in understanding the relationships between lines in a coordinate plane, which is essential for solving various geometry and algebra problems.

Review Questions

  • Explain the relationship between the slopes of two perpendicular lines.
    • The slopes of two perpendicular lines are negative reciprocals of each other. If the slope of one line is $m$, the slope of the perpendicular line will be $-1/m$. This means that if one line is increasing, the other line will be decreasing at the same rate. This unique relationship between the slopes of perpendicular lines is a key concept in understanding the properties of these lines and their applications in various mathematical contexts.
  • Describe how perpendicular lines can be used to find the equation of a line that passes through a specific point and is perpendicular to a given line.
    • To find the equation of a line that is perpendicular to a given line and passes through a specific point, you can use the fact that the slopes of perpendicular lines are negative reciprocals. First, you would need to know the slope of the given line. Then, you can calculate the slope of the perpendicular line by taking the negative reciprocal of the given slope. Finally, you can use the point-slope formula to write the equation of the perpendicular line, substituting the calculated slope and the coordinates of the given point.
  • Analyze the importance of identifying perpendicular lines in solving geometry and algebra problems.
    • The ability to identify and understand the properties of perpendicular lines is crucial in solving a variety of geometry and algebra problems. Perpendicular lines are fundamental in constructing geometric shapes, such as squares and rectangles, where all angles are 90 degrees. Additionally, the relationship between the slopes of perpendicular lines is essential for solving problems involving the equations of lines, finding the distance between parallel lines, and determining the orientation of lines in a coordinate plane. Mastering the concept of perpendicular lines and their applications can greatly enhance one's problem-solving skills in both geometry and algebra.
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