hú xián ㄏㄨˊ ㄒㄧㄢˊ 弧弦 谓开弓张弦。 汉 桓宽 《盐铁论·和亲》：“丁壮弧弦而出鬭，老者超越而入葆。”
在颈椎侧位片上测量椎体前缘序列弧线的弧弦距。
The distance of arc between vertebral anterior edge sequences was measured on lateral films of cervical vertebra.
弦的垂直平分线经过圆心，并且平分弦所对的两条弧。
A perpendicular bisector of a chord passes through the centre and bisects the arc.
空间圆弧粗插补用弦进给代替弧进给，即用空间直线代替圆弧。
The arch feed was replaced with bowstring feed in spatial arch interpolate, or circular arc was replaced with spatial straight line.
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