已知弦长2.2M,弦高0.5M,半径1.47M求弧长
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已知弦长2.2M,弦高0.5M,半径1.47M求弧长
![已知弦长2.2M,弦高0.5M,半径1.47M求弧长](/uploads/image/z/16848756-36-6.jpg?t=%E5%B7%B2%E7%9F%A5%E5%BC%A6%E9%95%BF2.2M%2C%E5%BC%A6%E9%AB%980.5M%2C%E5%8D%8A%E5%BE%841.47M%E6%B1%82%E5%BC%A7%E9%95%BF)
已知弦长L=2.2M,弦高H=0.5M,求弧长C,半径R?
弧所对的圆心角为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)
=0.5/2+2.2^2/(8*0.5)
=1.46M
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((2.2/2)/1.46)
=97.776度
C=PI*R*A/180=PI*1.46*97.776/180=2.492M
弧所对的圆心角为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)
=0.5/2+2.2^2/(8*0.5)
=1.46M
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((2.2/2)/1.46)
=97.776度
C=PI*R*A/180=PI*1.46*97.776/180=2.492M