In any circle, the measure of an inscribed angle is half the measure of its subtended arc, also the measure of the inscribed angle subtended by the diameter of the circle is 90 degrees
From the given figure
Since CE is the diameter of the circle
Since < CDE subtended by the diameter CE
The m < CDE = 90 degrees
Since < ECD is an inscribed angle subtended by the arc ED
m < ECD = 1/2 m arc ED
Since the measure of arc ED is 76 degrees
m < ECD = 1/2 x 76 = 38 degrees
In triangle CDE
m < CDE = 90 degrees
m < ECD = 38 degrees
Then
m < CED = 180 - 90 - 38
m < CED = 52 degrees