A Right-Angle Line
Part of the Graphs & Systems section of Coddy's Algebra journey. Lesson 35 of 64.
To draw a perpendicular line through a given point, first find the perpendicular slope. Then draw the line through the point with that slope, the same way you draw any line from a point and a slope. The slope of y = 1/2x + 1 is 1/2, so the perpendicular slope is -2. The perpendicular line through (0, -1) is y = -2x - 1.
The two lines cross once, at a right angle. The first line rises 1/2 for each step to the right. The second line falls 2 for each step to the right. The product of the two slopes is 1/2 × (-2) = -1.
Challenge
MediumThe line y = 1/2x - 1 is drawn. Draw the line perpendicular to it through (0, 3).
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Graphs & Systems
1The Coordinate Plane
Two Numbers, One PointThe Four QuadrantsPoints on the AxesMirror PointsRecap: The Plane4Slope-Intercept Form
y = mx + bThe Starting HeightWrite the EquationSolve for yDraw From Any FormRecap: y = mx + b7Parallel & Perpendicular
Same Slope, Never MeetThe Perpendicular SlopeA Right-Angle LineRecap: Two Relations2From Rule to Line
A Rule Makes PointsThe Points Line UpOn the Line or Not?Between the DotsRecap: Rule to Line