<h2>Explanation:</h2><h2></h2>
The diagram for this problem is shown below. Point E is the intersection of the two diagonals and we know that:
Every internal angle of any rectangle measures 90 degrees, so:
So:
So the measure of angle BEC can be found as follows:
We know that triangle ΔCEB is an isosceles triangle because the diagonals of any rectangle measure the same. So
The sum of internal angles of any triangle add up to 180 degrees, so: