The measure of angle BCD can be determined using various geometrical methods or given information about the angles involved in the triangle or polygon in which it lies.
For example, if you know the measures of angles A and D in a quadrilateral ABCD, you can use the property that the sum of the angles in a quadrilateral is 360 degrees to find the measure of angle BCD. Specifically, you would subtract the measures of angles A and D from 360 degrees to find angle BCD’s measure.
If angle BCD is part of a triangle, you would similarly use the fact that the sum of the angles in a triangle is always 180 degrees. With the measures of the other two angles, you can easily calculate angle BCD.
Please provide more information or a figure to give a specific value for the measure of angle BCD.