There's no b in the RHS because we substitute tan(b)=tan(45-a) =2 cos(a)/(cos(a)+sin(a))-1 into the expression instead of tan b.
The main idea of the solution is that we can gather pairs of angles which will give 45 summed up, like say 1+44, 2+43 and so on.
(1+tan(a) )( 1+ tan(b) )=[ (sin(a)+cos(a))/cos(a) ]*[2cos(a)/(cos(a)+sin(a))]=2
how did this happen...
why is there no 'b' in the RHS ??
can u please give the detailed steps of the above equation?