We have the next
AB is perpendicular with AD
DE is perpendicular with DC
angle B= angle ECD
angle ACD= 56°
We need to remember that the sum of the interior angles of a triangle is 180° and a right triangle is equal to 90°
So we have the next equation for angle B
[tex]m\angle B+56+90=180[/tex]
we isolate the angle B
[tex]m\angle B=180-90-56=34[/tex][tex]m\angle B=34\text{\degree}[/tex]
then for the angle BCE it forms an angle of 180° with angle BCA and ECD, therefor angle BCE is
[tex]m\angle BCE=180-56-34=90\degree[/tex]
ANSWER
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