Q.

Area of the parallelogram formed by the lines y=mx, y=mx+1, y=nx and y=nx+1 equals                     [2001]

1 |m+n|(m-n)2  
2 2|m+n|  
3 1|m+n|  
4 1|m-n|  

Ans.

(4)

The vertices, O(0,0), A(1m-n,mm-n), B(0,1)

Area (parallelogram OABC)=2×area (OAB)

=2×12|[0(mm-n-1)+1m-n(1-0)+0(0-mm-n)]|

=1|m-n|