Question

6 In the adjoining figure, seg AD parallel side BC , B-D-C
Prove that AB^ + CD² = BD + AC²​

Answer 1

if ABCD is a quadrilateral AC is diagonal and BD is diagonal

in ∆ABC by Pythagoras theoremBC square +AB square =AC square----------(1)

in ∆ ADC by Pythagoras theoremAC square =AD square+ DC square --------(2)

by adding equation(1)&(2)

AB square+ DC square = AC square +BD square

hence proved !