With point d as DE⊥AB in e,
And DC⊥CB, AB⊥CB,
∴∠DEB=∠ABC=∠DCB=90，
∴ Quadrilateral DEBC is a rectangle,
In Rt△ADE, ∠ α = 43, DE = CB =139m.
With point d as DE⊥AB in e,
And DC⊥CB, AB⊥CB,
∴∠DEB=∠ABC=∠DCB=90，
∴ Quadrilateral DEBC is a rectangle,
In Rt△ADE, ∠ α = 43, DE = CB =139m.
With point d as DE⊥AB in e,
And DC⊥CB, AB⊥CB,
∴∠DEB=∠ABC=∠DCB=90，
∴ Quadrilateral DEBC is a rectangle,
In Rt△ADE, ∠ α = 43, DE = CB =139m.
AE DE = tanα
∴AE=DE？ tanα
= 139? tan43
= 139×0.9325
≈ 129.62
∴ab = AE+EB = 129.62+ 1.4≈ 13 1.0m .
A: The height AB of this Millennium Tower is about 13 1.0 meters.
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