It can be obtained from the vertical nature of the plane: BE ⊥ plane D'AE.
∴ Advertising' ⊥ EB Point D'
2. As the vertical line of the bottom ABCE, the vertical foot is O, then:
Because, D'A=D'E= 1.
Therefore, o is the midpoint of AE.
The intersection o is perpendicular to AB, the vertical foot is G, and OG passes through AC to F; Connect D'G, make f the vertical line of D'G, make h the vertical foot, and connect AH.
Because D'O⊥ surface ABCE, so: D'O⊥AB.
Once again, AB⊥OG
So, AB⊥ surfaced.
So, AB⊥FH
FH⊥D'G, D'G and AB intersect at point g.
So, FH⊥ facing Abd
However, the point f is on the straight line AC.
Therefore ∠FAH is the angle formed by AC and surface ABD'
In rectangular ABCD, AB=2, BC= 1.
Therefore, AC=√5.
Since O is the midpoint of AE, AG/AB= 1/4.
And FG//BC
Therefore, AF/AC=AG/AB= 1/4, FG/BC=AG/AB= 1/4.
So AF=AC/4=√5/4, FG=BC/4= 1/4.
Also, DO'=AO=EO=√2/2, OG= 1/2.
So in Rt△D'OG, there is Pythagorean theorem: D g =√3/2.
And, Rt△D'OG∽Rt△FHG.
Therefore, fg/d 'g = FH/d 'o.
Namely: (1/4)/(√3/2)=FH/(√2/2)
Therefore, FH = 6/12.
Therefore, in Rt△AHF, AF=√5/4, FH=√6/ 12.
That is, sin ∠ fah = FH/AF = (√ 6/12)/(√ 5/4) = √ 30/15.