performance of the wall inlet a user must perform the following mathematical operations first the air density must be defined air density is shown in the equations as the symbol u03c1 a air density is represented in pounds force second squared per inch raised to the fourth power lb f s 2 in 4 the second step is to define the variable r 2 r 2 is defined using the following equation equ1 the value of r 2 is defined in inches next the value of h 2 must be defined the value of h 2 is defined by the following equation next the angle u03b8 1 must be defined u03b8 1 is defined using the following formula equ2 the angle u03b8 1 is represented in degrees next the angle u03b8 2 must be defined u03b8 2 is defined using the following formula equ3 the angle u03c6 1 is represented in degrees next the angle u03c6 1 must be defined u03c6 1 is defined using the following formula equ4 the angle u03c6 2 is represented in degrees next the angle u03c6 2 is defined by the following formula equ5 the angle u03c6 2 is defined by degrees the angle u03b2 is defined by the following formula equ6 the angle u03b2 is represented in degrees the next step is to define the geometrically determined constant c 1 c 1 is determined by the following equation equ7 c 1 is represented in lb f in the next step is to define the geometrically determined constant c 2 c 2 is determined by the following equation equ8 c 2 is represented in lb.