Answer
to proof - ∠B + ∠D = 180
Hence Proved
Work Step by Step
Sum of all the angles of a quadrilateral = 360
BA $\bot$AD AND BC $\bot$DC
$\angle$A = $\angle$C =90 *....(1)
$\angle$BAD +$\angle$ADC+$\angle$DCB+$\angle$CBA =360 $\angle$A +$\angle$B+$\angle$C+$\angle$D =360 90 + $\angle$B + 90 + $\angle$D = 360 ...USING (1)
$\angle$B + $\angle$D = 360- 180
$\angle$B + $\angle$D = 180
Hence proved
