perpendicular lines

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Perpendicular lines By Alma Villarreal

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Perpendicular lines. By Alma Villarreal. What are perpendicular lines?. Perpendicular lines are lines, segments, or rays that intersect to form right angles. Perpendicular to Parallel. Perpendicular rotate one line 90° parallel. - PowerPoint PPT Presentation

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Page 1: Perpendicular lines

Perpendicular lines

By Alma Villarreal

Page 2: Perpendicular lines

What are perpendicular lines?

Perpendicular lines are

lines, segments, or rays

that intersect to form right

angles.

Page 3: Perpendicular lines

Perpendicular to

Parallel

Perpendicular rotate one line 90° parallel

Question: What is the difference between perpendicular and parallel? Answer: 90 degrees (a right angle).If you rotate a perpendicular line by 90° it will become parallel (but not if it touches), and the other way around.

Page 4: Perpendicular lines

How to know if lines are perpendicular.

A line meeting another at a

right angle or 90° is said to be

perpendicular to it. Two lines

are perpendicular if the product

of their slopes is -1. Also, the

two intersecting lines form right

angles.

Page 5: Perpendicular lines

Perpendicular Lines in Algebra

If two nonvertical lines are perpendicular, then their slopes are negative reciprocals (opposite reciprocals) of one another, or the product of their slopes is –1.

Page 6: Perpendicular lines

Perpendicular Lines in Algebra

Conversely, if the slopes of two lines are opposite reciprocals of one another, or the product of their slopes is –1, then the lines are nonvertical perpendicular lines.

Page 7: Perpendicular lines

How Perpendicular Lines May Look

Perpendicular lines may also look like this. These lines are still perpendicular because all the angles are 90.

Page 8: Perpendicular lines

Perpendicular Lines

Lines do not have to intersect to be perpendicular. In the figure below, the two lines are perpendicular to each other even though they do not touch.

Page 9: Perpendicular lines

Perpendicular Lines

You can test if lines are perpendicular by extending the lines until they cross. If they do not cross, then they are parallel.

Page 10: Perpendicular lines

How to Draw Perpendicular Lines Steps 1 & 2

Step1: Start with a line and point K on that line.Step2: Set the compass width to a medium setting. The actual width does not matter..

Page 11: Perpendicular lines

Step 3

Step 3: Without changing the compass width, mark a short arc on the line at each side of the point K, forming the points P, Q. These two points are the same distance from K.

Page 12: Perpendicular lines

Steps 4 & 5

Step4: Mark off an arc on one side of the line.Step5: With the compass on P, set its width to any setting beyond K.

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Step6: Without changing the compass width, repeat from point Q so that the two arcs cross each other, creating the point R.Step7: Using the straight edge, draw a line from K to where the arcs cross.Step8: Done. The line KR just drawn is perpendicular to the line PQ at K.

Steps 6, 7 & 8

Page 14: Perpendicular lines