As shown in the figure, the quadrilateral ABCD is a square, PD ⊥ plane ABCD, EC ∥ PD, and PD = 2ec. (I) prove: plane PBE ⊥ plane PBD; (II) if the dihedral angle p-ab-d is 45 °, find the sine value of the angle between the straight line PA and the plane PBE

As shown in the figure, the quadrilateral ABCD is a square, PD ⊥ plane ABCD, EC ∥ PD, and PD = 2ec. (I) prove: plane PBE ⊥ plane PBD; (II) if the dihedral angle p-ab-d is 45 °, find the sine value of the angle between the straight line PA and the plane PBE

(1) Connect AC to BD at point F, take the midpoint n of Pb, connect en, FN. ∵ FBD as the midpoint, ∥ NF ∥ PD, NF = 12pd, EC = 12pd ∥ quadrilateral nfce as parallelogram ∥ ne ∥ FC ∥ DB ⊥ AC, PD ⊥ face ABCD, AC ⊂ face ABCD, ≁ AC ⊥ PD, PD ∩ BD = D, ≁ AC ⊥ PBD, namely FC