σ1/2=σx+σy2±√(σx−σy2)+τ2xy
σx=80sin60∘=69.28 kN/m2
σy=40 kN/m2
τxy=80cos60∘=40 kN/m2
Major principal stress(σ1)
=69.28+402√(69.28−402)2+402=97.23 kN/m2
τxy=τyx=βKN/m2
Although the values of α and β are not known yet the principal stresses are equal to each other being (5kN/m2). What is the radius of Mohr's circle?