In a quadrilateral ABCD, \angle A + \angle D = 90^°. Prove that AC^2+ BD^2 = AD^2 + BC^{ ^2} \lbrack Hint: Produce AB and DC to meet at E.\rbrack

In a quadrilateral ABCD, \angle A + \angle D = 90^°. Prove that AC^2+

1.	In a quadrilateral ABCD, \angle A + \angle D = 90^°. Prove that AC^2+ BD^2 = AD^2 + BC^{ ^2} \lbrack Hint: Produce AB and DC to meet at E.\rbrack
Answer» In a quadrilateral ABCD, \angle A + \angle D = 90^°. Prove that AC^2+ BD^2 = AD^2 + BC^{ ^2} \lbrack Hint: Produce AB and DC to meet at E.\rbrack