Question

Prove that If the diagonals of a parallelogram are of equal lengths,the parallelogram is a rectangle. pleaseeeeeeeeee fast

Answer 1

consider a parellolgram ABCD ACD IS CONGRUENT BDC AS AD=BC,AC=BD,DC COMMON BASE SO THESE ARE CONGRUENT AND IN PARALLELOGRAM ADJACENT ANGLES SUM IS 180 SO ANGLE D=ANG C 
ANGLE C+D =180 THIS IMPLY THAT 
C=D ANGLE 
AS IN PARALLELOGRAM  ALL THE ANGLES ARE 90DEGREE SO IT IS A RECTANGLE