### 18.1 Contour Integrals

## INTRODUCTION

In Section 9.8 we saw that the definition of the definite integral starts with a real function *y* = *f*(*x*) that is defined on an interval [*a*, *b*] on the *x*-axis. Because a planar curve is the two-dimensional analogue of an interval, we then generalized the definition of the definite integral to integrals of real functions of *two* variables defined on a curve *C* in the Cartesian plane. We shall see in this section that a complex integral is defined in a manner that is quite similar to that of a line integral in the Cartesian plane. In case you have not studied Sections 9.8 and 9.9, a review of those sections is ...

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