Search results
Results From The WOW.Com Content Network
Points in the polar coordinate system with pole O and polar axis L. In green, the point with radial coordinate 3 and angular coordinate 60 degrees or (3, 60°). In blue, the point (4, 210°). In mathematics, the polar coordinate system specifies a given point in a plane by using a distance and an angle as its two coordinates. These are
Conversely, the polar line (or polar) of a point Q in a circle C is the line L such that its closest point P to the center of the circle is the inversion of Q in C. If a point A lies on the polar line q of another point Q, then Q lies on the polar line a of A. More generally, the polars of all the points on the line q must pass through its pole Q.
A plane duality is a map from a projective plane C = (P, L, I) to its dual plane C ∗ = (L, P, I ∗) (see § Principle of duality above) which preserves incidence. That is, a plane duality σ will map points to lines and lines to points (P σ = L and L σ = P) in such a way that if a point Q is on a line m (denoted by Q I m) then Q I m ⇔ m ...
In geometry, a polar point group is a point group in which there is more than one point that every symmetry operation leaves unmoved. [1] The unmoved points will constitute a line, a plane, or all of space. While the simplest point group, C 1, leaves all points invariant, most polar point groups will move some, but not all points. To describe ...
Once the radius is fixed, the three coordinates (r, θ, φ), known as a 3-tuple, provide a coordinate system on a sphere, typically called the spherical polar coordinates. The plane passing through the origin and perpendicular to the polar axis (where the polar angle is a right angle) is called the reference plane (sometimes fundamental plane).
These four points determine a quadrangle of which P is a diagonal point. The line through the other two diagonal points is called the polar of P and P is the pole of this line. [19] Alternatively, the polar line of P is the set of projective harmonic conjugates of P on a variable secant line passing through P and C.
As it passes through the point where the tangent line and the curve meet, called the point of tangency, the tangent line is "going in the same direction" as the curve, and is thus the best straight-line approximation to the curve at that point. Similarly, the tangent plane to a surface at a given point is the plane that "just touches" the ...
The black lines show the tangents to E at the intersection points of E and its first polar with respect to Q meeting at Q. In algebraic geometry, the first polar, or simply polar of an algebraic plane curve C of degree n with respect to a point Q is an algebraic curve of degree n−1 which contains every point of C whose tangent line passes ...