A joint of a frame is subjected to three tensile force P, Q and R equally inclined to each other. If P is 10 tonnes, the other forces will be________.

A)
Q - R = zero
B)
Q + R = 10 tonnes
C)
Q = 10 tonnes and R = zero
D)
Q and R each is equal to 10 tonnes

Correct Answer :   Q and R each is equal to 10 tonnes