Correct Answer : Option (B) : U= [(σ₲+σ₂²+σ₃²)/2E] – (σâ‚σ₂+σ₂σ₃+σ₃σâ‚)2μ
Explanation : U= [(σÎ) â‚ + (σÎ) â‚‚+ (σÎ) ₃]/2 is the basic formula. After substituting values of Îâ‚, Îâ‚‚ and Î₃, we get the expression b.