What is the relationship between Angle of Attack and Angle of Incidence? The Angle of Incidence (AoI) of most GA planes is 6°. Assuming a plane with an Angle of Incidence of 6 degrees--

How do we calculate pitch attitude if we know the direction of the flight path and the Angle of Attack?  This is essentially a question about whether Angle of Attack is measured in relation to the chord line of the wing, or in relation to the longitudinal axis of the fuselage.

During takeoff, the Angle of Attack (AoA) is often 11° or more.  Is the 11° AoA measured in relation to the chord line of the wing, so that the pitch attitude at takeoff is 11 - 6 = 5 degrees?
Not really.

The angle of incidence is the angle between the chord of the wing and the longitudinal axis of the airplane.  But the plane is mostly free to pitch as necessary.  So if the best thing is for the wing to have an AOA of 11°, then it can pitch to that point.

Now if the angle of incidence were too different, it could increase drag on the climb-out, or the thrust angle might be less than optimal.  But there's no direct relationship.

The angle of incidence is a figure about the geometry of the plane.  The angle of attack is how the wing is oriented to the wind.  They don't "add" together.

If you did the math the other way (AOA - AOI), you'd find the angle the wind is making with respect to the airplane axis, not a figure that you tend to need.