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Perpendicular Lines

Perpendicular lines are lines, segments or rays that intersect to form right angles.

The symbol means is perpendicular to .

In the figure,


The right angle symbol in the figure indicates that the lines are perpendicular.

In three dimensions, you can have three lines which are mutually perpendicular.

The rays P T , T U and T W are perpendicular to each other.

Example :

If A B C D , find m E O D .

Since A B C D , m B O D = 90 ° .

By the Angle Addition Postulate,

m B O E + m E O D = m B O D

Let x ° be the measure of E O D .


35 ° + x ° = 90 ° .

Subtract 35 ° from each side.

x ° = 55 °


m E O D = 55 ° .