59. As shown in the figure, the diagonal $AC$ of square $ABCD$ intersects with $BD$ at point $O$. A right triangle $BCE$ is constructed inside the square with $BC$ as the hypotenuse, $\angle BEC=90^{\circ}$. If $CE=3, BE=5$, then the area of $\triangle OBE$ is $\qquad$
answer: 2.5