Equations of Parallel and Perpendicular Lines

Equations of Parallel and Perpendicular Lines

9th Grade · Math · 60 min

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Learning Objective

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

  • 1

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

  • 2

    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.

  • 3

    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.