Forces in equilibrium form a closed vector triangle

Steps:

• Identify forces at P: tension T in cable (upward at angle), compression C in rod (along rod toward wall), weight W of lamp (downward).
• For equilibrium, T + C + W = 0, so vectors form closed triangle.
• Sketch triangle: start with W vertical down, add T at cable angle, close with C opposite rod direction.
• Compare to options; D matches directions and closure.

Why D is correct:

• Vectors close per vector addition rule, with T opposing W partially and C balancing horizontally.

Why the others are wrong:

• A: Triangle doesn't close, violating equilibrium condition.
• B: Incorrect angles; T not at cable's direction.
• C: Vectors show tension in rod instead of compression.

Final answer: D