कैस्टिग्लियानो का दूसरा प्रमेय (Castigliano's second theorem) मुख्य रूप से संरचनात्मक विश्लेषण की निम्नलिखित में से किस विधि के अंतर्गत आता है?

During excavation support, if a raking shore begins to buckle when the load is uniformly distributed along its height, which internal stress condition primarily explains this failure?

Students build a physical model of a suspension bridge using strings and weights, then analyze tension distribution to derive a catenary curve. The teacher's approach BEST represents: