（1）∵∠ADC +∠DCB = 180°,∠DCB = 75°
?∴∠ADC = 105°
?∵∠ADC =∠ADE +∠EDC,∠EDC = 60°
?∴∠ADE = 105°-60°= 45°
（2）取DE的中點G,分別連接銀,DG
?∵∠EAD = 90°,∠ADE = 45°
?∴△EAD等邊三角形
?∴AE = AD
?∴AG⊥DE
?∵△ECD是一個等邊三角形
?∴CG⊥DE
?∴點A,G,C三點在同一條直線上
?△ABC∠B = 90°,∠BAC = 45°
∴△ABC是等腰直角三角形?
?∴AB = BC
（3）延長EB至H,使得EB = BH,連接的CH
?∵∠EBC = 90°,∠歐洲央行= 15°
?∴∠ECH = 2∠ECB = 30°,∠HEC =∠EHC = 75°
?∵∠FBC = 30°,∠DCB = 75°
?∴∠BFC = 75°
?∴△ECH△FBC類似
?∴FC/2EB = BC / CE
?∴FC = 2EB * BC / CE = 2 *是* cos15°= 2 * EC * sin15°* cos15°
?∴FC / DC = FC / EC = 2 * sin15°* cos15°= sin30°= 1/2
?∴DF / FC = 1