Snap a straight line to the perpendicular (90°) point on another straight line

Snap the lines

1. Draw 2 separate straight lines in a T-shape.

   To learn how, visit this link: Draw a straight line - (Line Tool)

    
2. Select the "Edit/Measure Tool" in the top toolbar.

   Quick Key: Or you can press the "Q" button on your keyboard.

    
3. (Optional - For Pro account users) In the Map View, you will see a pop-up on the left side. Select "Points".
    
4. Seek the approximate perpendicular (90°) point by dragging an end of the second line along the first line.
   When the two lines meet at the perpendicular point, a black circle will appear.

   The black circle notifies you the two lines will snap together exactly where the lines are perpendicular to each other.

See also

Snap a line’s end-point to a corner vertex of a rectangle/polygon

Snap a line’s end-point to the center of a circle

Snap a line’s end-point to the end-point on the edge of a circle