For a uniform triangular lamina, the weight acts at the centroid (G). The geometric property of a centroid is that its perpendicular distance from any side is exactly 1/3 of the altitude corresponding to that side.

To find $T_A$, take the torque about the opposite side, line BC.

• Distance of vertex A from line BC = $h_A = 3$ m.
• Distance of centroid G from line BC = $h_G = h_A/3 = 1$ m.
• Equation: $T_A(3) = mg(1) \implies T_A = mg/3$.

Since the geometry is symmetric with respect to weight distribution (centroid is the average of vertices), the calculation yields the same result for B and C.