Mach angle[′mäk ‚aŋ·gəl]
The vertex half angle of the Mach cone generated by a body in supersonic flight.
The acute angle between a weak shock wave and a free-stream airflow. Hence, at Mach 1, the Mach angle is 90°, and, thereafter, its value is equal to sin−1 × 1/M. It is represented by the symbol μ. See also Mach cone.