Again... AI blows, but ...

"Calculate the fraction of the circumference represented by the arc segment:Divide the arc segment length by the Earth's polar circumference (in inches):31.5 inches / 1,574,896,558.4 inches = 0.0000000200012759 Radians.

Which is kinda interesting, as it calculates the earths' circumference in Inches. 1.57 Billion inches.