As shown in the figure, in the rectangular ABCD, AE ⊥ BD, the perpendicular foot is e, ∠ DAE = 2 ∠ BAE, the degree of ball ∠ BAE and ∠ BDC
ABCD is a rectangle
∴∠BAD=90°
∵∠DAE=2∠BAE
∴∠DAE=60°,∠BAE=30°
∴∠ABD=60°
∵AB‖CD
∴∠BDC=∠ABD=60°
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