Im linken dreieck:
sin(54,2°) = 6,1cm / EB
EB = 6,1 cm / sin(54,2°) = 7,52 cm
und winkel AEB = 35,8°
also winkel BEC = 62,5° - 35,8° = 26,7°
cos( 26,7°) = EB / EC = 7,52 cm / EC
EC = 7,52cm / cos( 26,7°) = 8,42 cm
ED2 + CD2 = EC2
(4,9cm)2 + CD2 = ( 8,42 cm)2
gibt CD2 = 46,89cm2
CD = 6,85cm