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For the special antiderivatives involving trigonometric functions, see Trigonometric integral. [ 1 ] Generally, if the function sin x {\displaystyle \sin x} is any trigonometric function, and cos x {\displaystyle \cos x} is its derivative,
If the function f does not have any continuous antiderivative which takes the value zero at the zeros of f (this is the case for the sine and the cosine functions), then sgn(f(x)) ∫ f(x) dx is an antiderivative of f on every interval on which f is not zero, but may be discontinuous at the points where f(x) = 0.
Si(x) (blue) and Ci(x) (green) shown on the same plot. Sine integral in the complex plane, plotted with a variant of domain coloring. Cosine integral in the complex plane. Note the branch cut along the negative real axis. In mathematics, trigonometric integrals are a family of nonelementary integrals involving trigonometric functions.
Just as the definite integral of a positive function of one variable represents the area of the region between the graph of the function and the x-axis, the double integral of a positive function of two variables represents the volume of the region between the surface defined by the function (on the three-dimensional Cartesian plane where z = f(x, y)) and the plane which contains its domain. [1]
In integral calculus, the tangent half-angle substitution is a change of variables used for evaluating integrals, which converts a rational function of trigonometric functions of into an ordinary rational function of by setting = .
The inverse tangent integral is related to the Legendre chi function = + + + by: [1] Ti 2 ( x ) = − i χ 2 ( i x ) {\displaystyle \operatorname {Ti} _{2}(x)=-i\chi _{2}(ix)} Note that χ 2 ( x ) {\displaystyle \chi _{2}(x)} can be expressed as ∫ 0 x artanh t t d t {\textstyle \int _{0}^{x}{\frac {\operatorname {artanh} t}{t}}\,dt ...
A formula for computing the trigonometric identities for the one-third angle exists, but it requires finding the zeroes of the cubic equation 4x 3 − 3x + d = 0, where is the value of the cosine function at the one-third angle and d is the known value of the cosine function at the full angle.
Notice that if the thickness dx is infinitesimal, x varies only infinitesimally on the slice. We can assume that x is constant. [3] This integration is as shown in the left panel of Figure 1, but is inconvenient especially when the function h(y) is not easily integrated. The integral can be reduced to a single integration by reversing the order ...