Find the curvature of the curve defined by

r(t)=5cos(t),2sin(t)\displaystyle \vec{{r}}{\left({t}\right)}={\left\langle{5}{\cos{{\left({t}\right)}}},{2}{\sin{{\left({t}\right)}}}\right\rangle}

at t=π4\displaystyle {t}=\frac{\pi}{{4}}.