NX Measure angle between two tapered cylindrical or conical faces

When measuring the angle between two cylindrical or conical faces (created from Revolve feature), the result angle value is not always correct. Below is an example of the faces selected for measure and its unexpected value:

What is the best method to obtain an accurate angle measure between these two tapered cylindrical or conical faces?

Using the steps and options below will ensure accurate angle measurement between two tapered cylindrical or conical faces.

(1) Set the following options:

      Object to Measure: Vector

      Result Filter: toggle on "Angle" only

(2) In the Specify Vector selection, click on "Vector Dialog".

(3) In the Vector Dialog, switch setting to "Face/Plane Normal", select first tapered face.

(4) Now the option "Location on Face" appears. In "Specify Point" option, click on "Point Dialog" and set U Parameter=0 and V Parameter=1. OK the Point dialog.

(5) Now specify the next vector by clicking on "Vector Dialog".

(6) In the Vector Dialog, switch setting to "Face/Plane Normal", select second tapered face.

(7) Now the option "Location on Face" appears, in "Specify Point" option, click on "Point Dialog" and set U Parameter=0 and V Parameter=1. OK the Point dialog.