The load from a continuous footing of 1.8 metres width, which may be considered to be a strip load of considerable length, is 180 kN/m². Verify the maximum principal stress at 1.2 metres depth below the footing, if the point lies

(i)  directly below the centre of the footing,

(ii)  directly below the edge of the footing, and

(iii) 0.6 m away from the edge of the footing. What is the maximum shear stress at each of these points ? What is the absolute maximum shear stress and at what depth will it happen directly below the middle of the footing ?