英语词汇“focal property”的英英意思、用法、释义、翻译、读音、例句、短语、词组-英语词典

focal property n. Geometry any of various properties of a geometric figure that involve its focus or foci; esp. (a) the property that the lines though any point of an ellipse or hyperbola and its foci make equal angles with the tangent at that point; (b) the property that the line though any point on a parabola and its focus and the line that is parallel to the axis and runs through the same point make equal angles with the tangent at that point.

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1813 J. M. Good et al. Pantologia at Conic Sections Therefore FM = x + 1/2 c = AP + AF; which is the chief focal property of the parabola.

1840 J. Booth in London, Edinb., & Dublin Philos. Mag. 17 432 (title) On the focal properties of surfaces of the second order.

1867 W. Thomson & P. G. Tait Treat. Nat. Philos. I. i. 9 In drawing an ellipse, the focal property of the curve shows us that by fixing the ends of such a cord to the foci and keeping it stretched by a pencil, the latter will trace the curve.

1933 Math. Gaz. 17 278 The opening chapter deals with radial properties of the circle and focal properties of conic sections.

2012 P. Lockhart Measurement 179 There is a very pretty connection between these tangent lines and the focal property of the hyperbola.

单词	focal property
释义	> as lemmas focal property focal property n. Geometry any of various properties of a geometric figure that involve its focus or foci; esp. (a) the property that the lines though any point of an ellipse or hyperbola and its foci make equal angles with the tangent at that point; (b) the property that the line though any point on a parabola and its focus and the line that is parallel to the axis and runs through the same point make equal angles with the tangent at that point. ΚΠ 1813 J. M. Good et al. Pantologia at Conic Sections Therefore FM = x + 1/2 c = AP + AF; which is the chief focal property of the parabola. 1840 J. Booth in London, Edinb., & Dublin Philos. Mag. 17 432 (title) On the focal properties of surfaces of the second order. 1867 W. Thomson & P. G. Tait Treat. Nat. Philos. I. i. 9 In drawing an ellipse, the focal property of the curve shows us that by fixing the ends of such a cord to the foci and keeping it stretched by a pencil, the latter will trace the curve. 1933 Math. Gaz. 17 278 The opening chapter deals with radial properties of the circle and focal properties of conic sections. 2012 P. Lockhart Measurement 179 There is a very pretty connection between these tangent lines and the focal property of the hyperbola. extracted from focaladj. < as lemmas
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