Equations of Parallel and Perpendicular Lines

9th GradeMath60 min

Learning Objective

I can write an equation for a parallel or perpendicular line given another line and a point

Lesson Flow

Watch Video

5 min

Parallel and Perpendicular - Equations

Tyler Wallace

Guided Notes

12 min

Key concepts students will learn:

  • Parallel lines have the same slope, while perpendicular lines have opposite reciprocal slopes.

  • The point-slope equation, which is y - y₁ = m(x - x₁), can be used to find the equation of a line if you know the slope and a point on the line.

  • To find the equation of a parallel or perpendicular line, first identify the slope of the given line, then determine the slope of YOUR line. (Remember: you will need the SAME slope for parallel lines and the opposite reciprocal slope for perpendicular lines).  Finally, use the point-slope equation to find the new equation.

Practice

18 min

12 questions • Multiple choice & Short answer

Exit Ticket

5 min

Write the equation of a line that is perpendicular to the line y = -5x + 3 and passes through the point (5, -2).

Teacher Guide

Get the complete package:

  • Answer keys for all questions
  • Differentiation strategies
  • Extension activities
  • Printable student handouts