Here's a list of free websites that will draw perpendicular lines which you can download onto your computer...

GeoGebra (https://www.geogebra.org/)

Desmos (https://www.desmos.com/)

Mathway (https://www.mathway.com/)

Math Open Reference (https://www.mathopenref.com/)

Math Is Fun (https://www.mathsisfun.com/)

Wolfram Alpha (https://www.wolframalpha.com/)

Calculator Soup (https://www.calculatorsoup.com/)
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