Current location - Training Enrollment Network - Mathematics courses - Geometric proof of ninth grade mathematical circle
Geometric proof of ninth grade mathematical circle
When the AP passes through the AP at point B', the vertical line segment BB' passes through B'; The vertical line segment EE passing through E intersects with AP as AP' at point E'

Then E'E//DO//B'B

From the theorem that parallel lines bisect line segments, DE'/DB' =1/3 is obtained; EE'/BB'= 1/3

∠DE'E=∠DB'B=90

So ⊿DE'E∽⊿DB'B

Then ∠ Aduh =∠PDB got the certificate.