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In geometry, the radius of curvature, ''R'', of a curve at a point is a measure of the radius of the circular arc which best approximates the curve at that point. It is the inverse of the curvature. In the case of a space curve, the radius of curvature is the length of the curvature vector. In the case of a plane curve, then ''R'' is the absolute value of : where ''s'' is the arc length from a fixed point on the curve, ''φ'' is the tangential angle and is the curvature. If the curve is given in Cartesian coordinates as ''y(x)'', then the radius of curvature is (assuming the curve is differentiable up to order 2): : and | ''z'' | denotes the absolute value of ''z''. If the curve is given parametrically by functions ''x(t)'' and ''y(t)'', then the radius of curvature is : Heuristically, this result can be interpreted as : ==Examples== 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Radius of curvature (mathematics)」の詳細全文を読む スポンサード リンク
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