http://www.ck12.org Chapter 3. Parallel and Perpendicular Lines
3.2 Perpendicular Lines
Here you’ll learn about perpendicular lines, including their properties and how to construct them.
What if you were given a pair of lines that intersect each other at a right angle? What terminology would you use
to describe such lines? After completing this Concept, you will be able to define perpendicular lines. You’ll also be
able to apply the properties associated with such lines to solve for unknown angles
Watch This
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URL: http://www.ck12.org/flx/render/embeddedobject/52440CK-12 Foundation: Chapter3PerpendicularLinesA
Watch the portions of this video dealing with perpendicular lines.
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URL: http://www.ck12.org/flx/render/embeddedobject/1341James Sousa: Perpendicular Lines
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URL: http://www.ck12.org/flx/render/embeddedobject/1344James Sousa: Perpendicular Line Postulate
Guidance
Two lines areperpendicularif they meet at a 90◦, orright, angle. For a line and a point not on the line, there
is exactly one line perpendicular to the line that passes through the point. There are infinitely many lines that pass
throughA, but only one that is perpendicular tol. Recall that complementary angles add up to 90◦. If complementary
angles are adjacent, their nonadjacent sides are perpendicular rays. What you learn about perpendicular lines can
also be applied to this situation.