Normal stress on the plane inclined at 45°to x-axis will be

Question

Principal stresses at a point in plane stressed element are $\sigma _{x}$ = $\sigma _{y}$ = 500 kgf/cm². Normal stress on the plane inclined at 45°to x-axis will be                           

         (a) 0                                (b) 500 kgf/cm²

         (c) 707 kgf/cm²                (d) 1000 kgf/cm²