弧长S=915,弦长B=888,设圆半径为R.
由S=πRθ/180,B=2Rsin(θ/2)消去θ 得 Rsin(90S/πR)=B/2. (θ以度为单位)
此方程只含未知量半径R,可求.但因是超越方程,只能用试算法.把已知量代入得：Rsin(90×915/πR)=888/2,即
Rsin(26212.82/R)=444
设R=1080
左边=1080sin(26212.82/1080)=443.94