己知弧形弦長為L=1.43米,拱高是H=0.162米,求弧長C是多少?
弧半徑為R,弧所對的圓心角為A.
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)
=0.162/2+1.43^2/(8*0.162)
=1.659米
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((1.43/2)/1.659)
=49.92度
=49.92*PI/180
=0.87125弧度
C=A*R
=0.87125*1.659
=1.445米