A rigid-jointed plane frame is stable and statically determinate if ______. | Civil Engineering MCQ's

A.    (m + r) = 2j
B.    (m + r) = 3j
C.    (3m + r) = 3j
D.    (m + 3r) = 3j
where m is number of members, r is reaction components and j is number of joints

Ans: C