Determine a definite integral that represents the arc length of r=7cos(θ)\displaystyle {r}={7}{\cos{{\left(\theta\right)}}}, 0θπ2\displaystyle {0}\le\theta\le\frac{\pi}{{2}}.

0π2\displaystyle {\int_{{0}}^{{\frac{\pi}{{2}}}}}      dθ\displaystyle {d}\theta