Determine what diagram is the correct Mohr's circle for the given strain state.

The first step in constructing a Mohr's Circle is to locate its center along the normal strain axis (x-direction).

     center = (ε_x + ε_y)/2 = (100 + 400)/2 = 250μ

Next, a point on the circle can be plotted,

     (ε_x, τ_xy/2) = (400μ, 100μ)
or
     (ε_y, -τ_xy/2) = (100μ, -100μ)

These points are shown on the diagram on the left. Now the radius can be determined,

      R² = 100² + (400 - 250)²
      R = 180.3μ = 180.3 × 10^-6

The current stress state is represented by a line at an angle of

     θ = tan^-1(100/15) = 33.69^o

Diagram 3 is the correct representative of Mohr's circle for the given strain state.