弓形面积=扇形面积-等腰三角形面积
={2*arcsin[(r^2-(r-h)^2)^(1/2)/r]}*(pi*r^2/(2pi))
-(r-h)*(r^2-(r-h)^2)^(1/2)
=r^2*arcsin[(h/r)*((2r/h)-1)^(1/2)]-(r-h)h*((2r/h)-1)^(1/2)
1.当r=0.672,h=0.49
弓形面积=0.672^2 *arcsin[(0.49/0.672)*((2*0.672/0.49)-1)^(1/2)]
-(0.672-0.49)*0.49*((2*0.672/0.49)-1)^(1/2)
=0.5855-0.1177
=0.4678 m^2
2.当r=0.647,h=0.28
弓形面积=0.647^2 *arcsin[(0.28/0.647)*((2*0.647/0.28)-1)^(1/2)]
-(0.647-0.28)*0.28*((2*0.647/0.28)-1)^(1/2)
=0.4051-0.1956
=0.2095 m^2