The angle of attack is defined as the acute angle formed between which two lines?

• A. The chord line of the airfoil and the direction the air strikes the airfoil.
• B. The wing span and the air stream.
• C. The leading edge and trailing edge.
• D. The fuselage axis and the relative wind.

Answer: (A)

Angle of attack is how much the wing is tilted into the oncoming air. It’s the acute angle between the airfoil’s chord line (a straight line from the leading edge to the trailing edge) and the relative wind—the direction the air is flowing toward the wing. This reference is key because lift is created by how the air meets the wing, which is determined by that angle, not by the wing’s span or by the edges themselves. The other options describe different ideas (span, edges, or fuselage alignment) that don’t define how the wing meets the airflow.