Q: 2  If the diagonals of a parallelogram are equal, then show that it is a rectangle.
 
                
                  Given: ABCD is a parallelogram with AC=BD.
To prove: ABCD is a rectangle.
Proof : In ABC and 
BAD,   

BC= AD (Opposite sides of parallelogram)
AC=BD (Given )
AB=AB (common)
 ABC 
 
BAD   (By SSS)
               (CPCT)
and   (co - interior angles)
   
   
Hence, it is a rectangle.