The resultant lift is perpendicular to the chord of the wing section. If the angle of attack increases as speed decreases, the sine of the lift vector is adding to the total drag, while cosine of the lift vector is the useful lift you get. The larger the AOA, the larger the induced drag which is equal to sine AOA. Wing tip vortices also increases with AOA.
[This message has been edited by Old Dog (edited 21 November 2000).]