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In the theory of quadratic forms, the parabola is the graph of the quadratic form x 2 (or other scalings), while the elliptic paraboloid is the graph of the positive-definite quadratic form x 2 + y 2 (or scalings), and the hyperbolic paraboloid is the graph of the indefinite quadratic form x 2 − y 2. Generalizations to more variables yield ...
In this position, the hyperbolic paraboloid opens downward along the x-axis and upward along the y-axis (that is, the parabola in the plane x = 0 opens upward and the parabola in the plane y = 0 opens downward). Any paraboloid (elliptic or hyperbolic) is a translation surface, as it can be generated by a moving parabola directed by a second ...
To see how this might come about, consider the variety V(y − x 2). If we draw it, we get a parabola. As x goes to positive infinity, the slope of the line from the origin to the point (x, x 2) also goes to positive infinity. As x goes to negative infinity, the slope of the same line goes to negative infinity. Compare this to the variety V(y ...
The scale factors for the parabolic coordinates (,) are equal = = + Hence, the infinitesimal element of area is = (+) and the Laplacian equals = + (+) Other differential operators such as and can be expressed in the coordinates (,) by substituting the scale factors into the general formulae found in orthogonal coordinates.
The definition of a projective quadric in a real projective space (see above) can be formally adapted by defining a projective quadric in an n-dimensional projective space over a field. In order to omit dealing with coordinates, a projective quadric is usually defined by starting with a quadratic form on a vector space.
Semicubical parabola for various a. In mathematics, a cuspidal cubic or semicubical parabola is an algebraic plane curve that has an implicit equation of the form = (with a ≠ 0) in some Cartesian coordinate system. Solving for y leads to the explicit form =,
A parabolic segment is the region bounded by a parabola and line. To find the area of a parabolic segment, Archimedes considers a certain inscribed triangle. The base of this triangle is the given chord of the parabola, and the third vertex is the point on the parabola such that the tangent to the parabola at that point is parallel to the chord.
Let P = (x, y) and let ψ be the angle between SB and the x-axis; this is equal to the angle between ST and J. By construction, PT = a, so the distance from P to J is a sin ψ. In other words a – x = a sin ψ. Also, SP = a is the y-coordinate of (x, y) if it is rotated by angle ψ, so a = (x + a) sin ψ + y cos ψ. After simplification, this ...