∠ABC=12∠BGD,AB=AC,DE=EC,BG=GD\angle ABC=\frac{1}{2}\angle BGD,AB=AC,DE=EC,BG=GD∠ABC=21∠BGD,AB=AC,DE=EC,BG=GD
求证 ∠AEG=90∘\angle AEG=90^\circ∠AEG=90∘
