You can use the Horizontal/Vertical constraint to create a horizontal or vertical relationship between linear sketch elements. Horizontal and vertical directions in a sketch are aligned with the axes of the sketch plane.
To create a Horizontal/Vertical constraint:
Select a single or multiple lines on the same sketch plane.
From the constraints menu, select Horizontal/Vertical. Note: The line(s) are aligned with the axis closest to their original direction.
Learn more by watching the video below:
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You can automatically create Horizontal/Vertical constraints while sketching when the constraint setting for Auto-constraining is turned on. For more information, visit Constraint Settings.