Question

Using vectors prove that if the diagonals of a parallelogram are equal

Answer 1

Given That: Let OACB be the parallelogram and diagonals are equal

 

To Prove: if diagonals are equal, OACB is a rectangle.

 

Construction: draw a parallelogram and join the diagonal.

 

Proof:

 Let and, then (parallelogram law)



Since (given)

So,