i.4.48 Curvilinear integrals

Condition: Calculate the curvilinear integral along a curve specified parametrically: \[ \begin{array}{l} \int_{L} y d x+x d y=I, \quad \text { where } L: x=R \cos t \\ y=R \sin t, \quad 0 \leq t \leq \frac{\pi}{2} \end{array} \]