Question

in case of rhombus proof
(AB + BC+CD+DA)=(AC^2+BD^2)​

Answer 1

Let the diagonals AC and BD of rhombus ABCD intersect at O. Since the diagonals of a rhombus bisect each other at right angles. ∴ ∠AOB = ∠BOC = ∠COD = ∠DOA = 90º and AO = CO, BO = OD. Since ∆AOB is a right triangle right-angle at O.