The area enclosed by a parametric curve with endpoints is given by the line integrals:
The projection of an object at a given angle is made up of a set of line integrals.
The left side is now the sum of three line integrals along the bounds of the causality region.
Such integrals are known as line integrals and surface integrals respectively.
Various different line integrals are in use.
Direct methods involve the calculation of the integral by means of methods similar to those in calculating line integrals in several-variable calculus.
By properties of line integrals, and .
The gradient theorem implies that line integrals through irrotational vector fields are path independent.
In continuous tomography both the domain and the range of the function are continuous and line integrals are used.
The "circulation of the fields" can be interpreted from the line integrals of the fields around the closed curve Σ: