PQRS and EFRS are on the same base SR and between the same parallels EF and SR.
So their areas are equal
i.e. ar (PQRS) = ar (EFRS) ….(i)
Also ar (∆MFR) = \(\frac { 1 }{ 2 }\) ar (EFRS) …(ii)
From equation (i) and (ii), we get
ar (MFR) = \(\frac { 1 }{ 2 }\) ar (PQRS).
Hence proved.