For the soil element below, given that

${}_x=$

$4\mathrm{.}8$ kPa

${}_V=$

$6$ kPa

${}_{xy}=$

$3\mathrm{.}6$ kPa

$=$

$30$

Note, pay attention to the direction of the angle and shear stress on basal plane

Finish the problems below.

$1.)$ On plane $AB$

Normal stress ${}_n=$

Shear stress ${}_n=$

$2.)$ On principle plane:

Principle plane angle is $=$

Major princile stress ${}_1=$

Minor princile stress ${}_3=$