Problem 1 The element is subjected to plane stress. To determine the normal stress over section AB of the element, the following transformation equation is used: \sigma_{x^{\prime}}=\frac{\sigma_{x}+\sigma_{y}}{2}+\frac{\sigma_{z}-\sigma_{y}}{2} \cos 2 \theta+\tau_{x y} \sin 2 \theta Which of the following is the correct to be used?

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