∴AB∥CD,AD∥BC
∴∠BAD+∠CDA= 180,
∠ABC+∠DCB= 180,
∠ADC+∠BCD= 180
∫AE, BG, DE and FG are respectively
The angular bisector of ∠BAD∠ABC∠CDA∠BCD.
∴∠E= 180 -(∠EAD+∠EDA)
= 180 - 1/2(∠BAD+∠CDA)
= 180 -90 =90
Similarly, ∠ g = 90, ∠ ghe = ∠ CHD = 90.
∴ quadrilateral EFGH is a rectangle.