Geometry problem below was found in Facebook group "PI love math".
Question: prove that x=22.5
draw perpendicular bisector of AB. E is intersection with BC.
LAEC=x+x=2x.....(exterior angle of ΔABE)
draw perpendicular bisector of AE, F is intersection with extended DE.
FC is bisector of interior angle F.
DC is bisector of exterior angle D.
conclusion: AC is bisector of exterior angle A.
observe angles at point A.
3x + 3x + 90-2x = 180