problem with checking of angle

we have a product like a Fin(image attach) it has 10 wings and on each wing there is 1 degree angle to the centre line.I make plane on every wing and take one cylinder in the fin bore and then open alignment tab and level bore to Z plus and again origin it with xyz. then open Angle measurement tab I select plane and see the angle in z axis also check 3 D but every time i take a plane the angles goes differ .
Did anyone please guide me how to check this angle