A cantilever truss is loaded and supported as shown in the figure given below. Find the out value of P, which would produce an axial force of magnitude 3KN in member AC.

Sol.: Find out in the member AC, DC and DF

Let T₁  = Force in member AC
 T₂  = Force in member DC

T₃  = Force in member DF

Draw the section line, which cut member AC, DC, and DF.

Consider the right portion of truss, as Force P is in the right portion. Taking moment about D,

∑M_D = 0

- T₁  X AB + P X (AC - AD) + P X (AE - AD) = 0

-3 X 2 + P X 1.5 + P X 4.5 = 0

P = 1KN                           .......ANS