X pj1af2 4id2 1L 1kR gT rearrange the equation to SOLVE f

X = pj(1/a)*(f2 / (4id)^2)( 1/L )( 1/kR )(g/T)

rearrange the equation to SOLVE for d

X = pj(1/a)*(f2 / (4id)^2)( 1/L )( 1/kR )(g/T)

Divide both sides by X

1 = pj(1/a)*(f2 / (4id)^2)( 1/L )( 1/kR )(g/T*X)

multiply both sides by d^2

d^2 = pj(1/a)*(f2 / (4i)^2)( 1/L )( 1/kR )(g/T)

take square root of both sides:

d = (f2/4.i) sqrt{ pj(1/a).( 1/L )( 1/kR )(g/T) }