Evaluate the Line Integral of the Function Over the Given $f ( x , y ) = x$

Essay

Evaluate the line integral of the function over the given curve: $f ( x , y ) = x$ and the curve C is given by $\vec { r } ( t ) = \langle \cos ( t ) , \sin ( t ) \rangle , 0 \leq t \leq \frac { \pi } { 2 }$