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The secant lines PQ are the approximations to the tangent line. In calculus, this idea is the geometric definition of the derivative. The tangent line at point P is a secant line of the curve. A tangent line to a curve at a point P may be a secant line to that curve if it intersects the curve in at least one point other than P.
The geometrical idea of the tangent line as the limit of secant lines serves as the motivation for analytical methods that are used to find tangent lines explicitly. The question of finding the tangent line to a graph, or the tangent line problem, was one of the central questions leading to the development of calculus in the 17th century.
The derivative of a function is then simply the slope of this tangent line. [b] Even though the tangent line only touches a single point at the point of tangency, it can be approximated by a line that goes through two points. This is known as a secant line. If the two points that the secant line goes through are close together, then the secant ...
A tangent line t to a circle C intersects the circle at a single point T. For comparison, secant lines intersect a circle at two points, whereas another line may not intersect a circle at all. This property of tangent lines is preserved under many geometrical transformations, such as scalings, rotation, translations, inversions, and map ...
Here, the poles are the numbers of the form (+) for the tangent and the secant, or for the cotangent and the cosecant, where k is an arbitrary integer. Recurrences relations may also be computed for the coefficients of the Taylor series of the other trigonometric functions.
The tangent line is the best linear approximation of the function near that input value. For this reason, the derivative is often described as the instantaneous rate of change , the ratio of the instantaneous change in the dependent variable to that of the independent variable. [ 1 ]
For instance, with respect to a conic (a circle, ellipse, parabola, or hyperbola), lines can be: tangent lines, which touch the conic at a single point; secant lines, which intersect the conic at two points and pass through its interior; [5] exterior lines, which do not meet the conic at any point of the Euclidean plane; or
Secant is a term in mathematics derived from the Latin secare ("to cut"). It may refer to: a secant line, in geometry; the secant variety, in algebraic geometry; secant (trigonometry) (Latin: secans), the multiplicative inverse (or reciprocal) trigonometric function of the cosine