已知弦长L=9.64米,弦高H=1米.求面积S?
弧半径为R,圆心角为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)
=1/2+9.64^2/(8*1)
=12.1162米
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((9.64/2)/12.1162)
=46.88度
扇形面积S=PI*R^2*A/360
=PI*12.1162^2*46.88/360
=60.06平方米