i.4.46 Curvilinear integrals

Condition: Calculate the curvilinear integral over the length of the arc \( \int_{L} f(x, y) d l \) of the function \( f(x, y) \). \[ \begin{array}{l} f(x, y)=y^{2}, \quad L: x=a(t-\sin t) \\ y=a(1-\cos t), \quad t \in[0 ; 2\pi] . \end{array}\]