In flight mechanics and aerodynamics, the “mean aerodynamic chord” (MAC) refers to an average chord length that is used to represent the wing planform of an aircraft with a trapezoidal wing shape. The mean aerodynamic chord provides a way to simplify the complex geometry of a trapezoidal wing into a single representative value, which is useful for various aerodynamic calculations and analyses.
Cr means root chord
(λ) means taper ratio