Problem $10)$ The average stress conditions right underneath the footing that supports column C$7$ for a

certain load combination are represented by the element below. For this case, calculate the principal

stresses, the maximum shear stress and the angle formed by the normal to this plane and the horizontal

direction. and as a part question no $11$ as soon as possiable please

Problem $11)$ Consider the state of stress from Problem $10$ again. If the shear strength of soil under

column C $8$ is $120$ kPa $,$ is the soil under the footing at failure?