<image>As shown in the figure, ∠1 = ∠2, CF ⊥ AB, DE ⊥ AB, prove: FG ∥ BC.  Proof: ∵ CF ⊥ AB, DE ⊥ AB _(Given) ∴ ∠BED = 90°, ∠BFC = 90° (______________) ∴ ∠BED = ∠BFC (______________) ∴ ED ∥ FC ____ (_________________________) ∴ ∠1 = ∠BCF _ (_________________________) ∵ ∠2 = ∠1 ___(_Given) ∴ ∠2 = ∠BCF _ (_____________) ∴ FG ∥ BC ____ (_________________________)_