In a rectangular element subjected to like principal tensile stresses 'ρ′1 and ′ρ2' in two mutually perpendicular directions X and Y, the maximum shear would occur along the
where, θ is the angle of inclination of the plane of major principal stress.
sin2θ=1
∴θ=45∘and135∘
with y-direction (planeofp1)