Why Is the Unit Load Not Considered When Moved to B in Truss Analysis?

[fonseh]

Homework Statement

Pls refer to the second photo , the red line part ...I don't understand the meaning of when 1 unit load move at C , the unit load is inclusive in the right system... I can understand the FBG sin45 + 1 = RE

Homework Equations

The Attempt at a Solution

When the in unit load move at b , shouldn't the equation become like this ? FBG sin45 + 1 = RE

Why the author didn't consider the unit load when the unit load is moved to B ?

 

[fonseh]

When 1 unit load moved to B , the equation of vertical forces should be like this , right ? 1-FBGsin45 - FBH = 0.25 , i don't understand why the author used 0.25-FGBsin45 = 0 , by dosing so , he ignored the unit load and also the FBH... How can it be correct ?

 

[fonseh]

BUMP