The radius of the arc is R.

R^2=(R-H)^2+(L/2)^2

R^2=R^2-2*R*H+H^2+L^2/4

2*R*H=H^2+L^2/4

R=H/2+L^2/(8*H)

=340/2+ 1930^2/(8*340)

= 1539.449

A = 2 * arcsine ((L/2)/R)

= 2 * Arcsine ((1930/2)/ 1539.449)

=77.636 degrees

=77.636*PI/ 180

= 1.355002 radian

c = R * A = 1539.449 * 1.355002 = 2085.96