Let P, Q, R and S be the points on the plane with position vectors
−2^i−^j,4^i,3^i+3^j and −3^i+2^j, respectively. The quadrilateral PQRS must be a
parallelogram, which is neither a rhombus nor a rectangle
mPQ=16,mSR=16,mRQ=−3,mSP=−3
⇒ Parallelogram, but neither PR=SQ nor PR⊥SQ
∴ So, it is a parallelogram, which is neither a rhombus nor a rectangle.