For the parallelogram OPQR shown in the sketch, \(\overline {{\rm{OP}}} = a\hat i + b\hat j\) and \(\overline {{\rm{OR}}} = c\hat i + d\hat j\) .The area of the parallelogram is
1
ad - bc
2
ac + bd
3
ad + bc
4
ab - cd
For the parallelogram OPQR shown in the sketch, \(\overline {{\rm{OP}}} = a\hat i + b\hat j\) and \(\overline {{\rm{OR}}} = c\hat i + d\hat j\) .The area of the parallelogram is