Question

if the diagonas of a parellalogram are equal then proof that it is a rectangle

Answer 1

LET PARELLALOGRAM 's DIAGONAL BE X
THEN,
X = √L×L +B×B
AND RECTANGLE's DIAGONAL
√L×L+B×B
HENCE PROOFED

Answer 2

GIVEN a parallelogram ABCD in which diagonals AC=BD. TO PROVE ABCD is a rectangle. PROOF. IN triangle ABC andDCB,AB=DC (opposite sides of llgm) ,BC =CB(common)and AC=DB(given). so,triABC
congruent triDCB. therefore,angle ABC=angle DCB equation(1).But DCllABandCB cuts them. so angleABC+angleDCB=180°(co.int angle) .now angleABC=angleDCB=90°(using1).thus ABCD is a llgm one of whose angles is90°.hence ABCD is a rectangle.