Problem $3$ For pin$-$joined truss ABCDE shown below subjected the to the applied load $P,$ compute the

following:

a$)$ Verify that this truss is indeed statically determinate

b$)$ Compute the supports reaction forces

c$)$ Compute the horizontal & vertical displacements of joint $E.$

Assume all members have the same values of $E$ and $A.$ Display your answer completely in terms of the

given parameters $E,A,L$ and $P.$

hint: use Castigliano's theorem