For Principal planes, a plane stress element has σx=85 MPa\sigma_x=85\,\mathrm{MPa}σx=85MPa, σy=24 MPa\sigma_y=24\,\mathrm{MPa}σy=24MPa, and τxy=36 MPa\tau_{xy}=36\,\mathrm{MPa}τxy=36MPa. What is the maximum principal stress?