As shown in the figure, there are two slides of the same length. The height AC of the left slide is equal to the length DF of the right slide in the horizontal direction. The relationship between the inclination angles ∠ ABC and ∠ DFE of the two slides is () A. ∠ABC=∠DFEB. ∠ABC＞∠DFEC. ∠ABC＜∠DFED. ∠ABC+∠DFE=90°

As shown in the figure, there are two slides of the same length. The height AC of the left slide is equal to the length DF of the right slide in the horizontal direction. The relationship between the inclination angles ∠ ABC and ∠ DFE of the two slides is () A. ∠ABC=∠DFEB. ∠ABC＞∠DFEC. ∠ABC＜∠DFED. ∠ABC+∠DFE=90°

∵ BC = EF, AC = DF, ∵ cab = ∠ FDE = 90 °≌ ABC ≌ def (HL) ∵ BCA = ∠ DFE, and ∵ in RT △ ABC, ∵ ABC + BCA = 90 °≌ ABC + DFE = 90 °. So D

Known: as shown in the figure, in △ ABC, de ‖ BC, EF ‖ AB, try to judge whether addb = bffc is true? And explain the reason

Addb = bffc holds for the following reasons: ∵ de ∥ BC, ∵ addb = AEEC. ∵ EF ∥ AB, ∵ bffc = AEEC. ∵ addb = bffc