作业帮已知弦长70,求弧长?
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已知弦长70,求弧长?
已知弦长70,求弧长?
已知弦长70,求弧长?
已知弦长L=70,弧高H=30,求弧长C?
弧半径为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)
=30/2+70^2/(8*30)
=35.417
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((70/2)/35.417)
=162.41度
=162.41*PI/180
=2.83451弧度
C=A*R
=2.83451*35.417
=100.389