You are asked to solve the fixed$-$fixed indeterminate beam shown below using the Force Method. $($a$)$ write down the compatibility equations, and $($b$)$ compute the rotation$/$angular flexibility coefficients ${}_{AA},{}_{BB},{}_{AB},$ and ${}_{BA}$ when you consider support moments at A and B as redundant. Now for a second scenario, you have decided to consider vertical support reactions at A and $B$ as redundant. For such case $($c$)$ write down the compatibility equations and $($d$)$ compute the flexibility coefficients $f_{AA},f_{BB},f_{AB},$ and Fba