the asngle between the diagonals of the parallelogram formed by the lines x/a+y/b=1,x/b+y/a=1,x/a+y/b=2,x/b+y/a=2 is_?

This method may be a bit lengthy bt u'll get the answer using this.

first find all the vertices of the parallelogram........

by the intersection of all the adjacent sides of the parallelogram.

After that with the help of opposite vertices obtain the equation of the diagonals by two point form.

After that u cn obtain the angle b/w the lines by using tan(theta)=mod of (m1-m2)/(1+m1m2)

where m1 and m2 are the slopes of both the diagonal.........

WILL FIND SME SHORT METHOD TOO AND WILL SEND IT TO U.......... IF POSSIBLE.

I HOPE THIS WILL SOLVE UR PROB........