To Measure Perpendicular Distance from a Segment of an Element

Select the Measure Distance tool ( Drawing > Analyze > Measure ).
In the tool settings window, set Method to Perpendicular.
Turn on Segment Only.
Select the element at the segment that is to be used.
Enter a data point.
The perpendicular distance between the element and this point are displayed in the Distance field. A temporary line is displayed as a visual aid but is not placed in the design. If the data point is not within the limits of the selected segment, then the projection of the segment is used.
Do one of the following:

Enter another data point(s) to define other perpendicular measurements.

or
Reset to return to step 4.

If the element is a line string, shape, curve, complex chain, or complex shape, the distance is measured perpendicular to the segment identified in step 3.