$1\mathrm{.}12.$ The strain state at a point is given as $lo{n}_x=900lon,lo{n}_y=100lon,{}_{xy}=-600lon.$ Using Mohr's

strain circle method, determine $($a$)$ the maximum shear strain, $($b$)$ the principal strains

and principal angle, and $($c$)$ the strain components with respect to the $x^{\text{'}}{y}^{\text{'}}$ coordinate sys$-$

tem, achieved by rotating the $x$ axis $45CCW.$