Measurement Of Angles On Holes

Introduction
To creating angles for holes it's not possible to use vertical or horizontal center lines (false/true) from the properties of the view. Help lines or/and helping points are necessary.

Proceeding:
1.Setting center lines on holes:

There are some possibilities to create a center line for holes. At first the lines or points on the hole must be selected. Behind them the tool     or         from the tool bar is creating the center line. Please show the figures below.