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# condition of orthogonality

Let two straight lines of the $xy$-plane have the slopes $m_{1}$ and $m_{2}$. The lines are at right angles to each other iff $m_{1}$ and $m_{2}$ are the opposite inverses of each other, i.e. iff

$m_{1}m_{2}=-1.$ |

Example. The lines $y=(1+\sqrt{2})x$ and $y=(1-\sqrt{2})x$ are at right angles to each other.

Defines:

opposite inverse

Keywords:

straight line, slope

Related:

OrthogonalCurves, InverseNumber, OppositeNumber, NormalLine, AngleBetweenTwoLines, PerpendicularityInEuclideanPlane, Evolute2, ExampleOfFindingCatacaustic

Synonym:

condition of perpendicularity

Type of Math Object:

Result

Major Section:

Reference

Parent:

Groups audience:

## Mathematics Subject Classification

15A57*no label found*51F20

*no label found*

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