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Parabola: pin string construction. The definition of a parabola by its focus and directrix can be used for drawing it with help of pins and strings: [9] Choose the focus and the directrix of the parabola. Take a triangle of a set square and prepare a string with length | | (see diagram).
String art, created with thread and paper A string art representing a projection of the 8-dimensional 4 21 polytope Quadratic Béziers in string art: The end points (•) and control point (×) define the quadratic Bézier curve (⋯). The arc is a segment of a parabola.
An involute of a curve is the locus of a point on a piece of taut string as the string is either unwrapped from or wrapped around the curve. [1] The evolute of an involute is the original curve. It is generalized by the roulette family of curves. That is, the involutes of a curve are the roulettes of the curve generated by a straight line.
The definition of a hyperbola by its foci and its circular directrices (see above) can be used for drawing an arc of it with help of pins, a string and a ruler: [9] Choose the foci F 1 , F 2 {\displaystyle F_{1},F_{2}} and one of the circular directrices , for example c 2 {\displaystyle c_{2}} (circle with radius 2 a {\displaystyle 2a} )
A family of conic sections of varying eccentricity share a focus point and directrix line, including an ellipse (red, e = 1/2), a parabola (green, e = 1), and a hyperbola (blue, e = 2). The conic of eccentricity 0 in this figure is an infinitesimal circle centered at the focus, and the conic of eccentricity ∞ is an infinitesimally separated ...
The string compass drawing tool has various modifications and designs, and this construction method is reminiscent of string-based methods for creating ellipses (with two fixed pins). Yet another mechanical method is a variant of the previous string compass method, providing greater precision and more flexibility.
This includes, by clearing denominators, the case where F(t, x, y) is a rational function in t. In this case, the definition amounts to t being a double root of F ( t , x , y ), so the equation of the envelope can be found by setting the discriminant of F to 0 (because the definition demands F=0 at some t and first derivative =0 i.e. its value ...
Holomorphic function: complex-valued function of a complex variable which is differentiable at every point in its domain. Meromorphic function: complex-valued function that is holomorphic everywhere, apart from at isolated points where there are poles. Entire function: A holomorphic function whose domain is the entire complex plane.