Solution: ∠BDE=∠C for the following reasons:

Because AD⊥BC and FG⊥BC

So AD∨FG (in the same plane, two straight lines perpendicular to the same straight line are parallel)

So ∠ 1=∠3 (two straight lines are parallel and have the same angle).

Similarly ∠ 1=∠2

So < 3 = < 2.

So AC Σ ed

So ∠ BDE = ∠ C.

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