20. As shown in the figure, at △ABC, ∠ ACB = 90, AC = BC =10, at △DCE, ∠ DCE = 90, DC = EC = 6°, point D is on the line segment AC, and point E is on the extension line segment BC. Wind △DCE

explain

Let E'F be vertical and the angle ECE'=60 degrees CF= 1/2CE'=3 E'F=3 pieces 3 BE'= 14. Find NC= 15 roots according to the area. Extend BE to B' so that B'c = BC△ACM ~△