Stress path equation for tri-axial test upon application of deviatoric stress is, $q=10 \sqrt{3}+0.5p$. The respective values of cohesion, $c$ (in kPa) and angle of internal friction, $\phi$ are:
- $20$ and $20^{\circ}$
- $20$ and $30^{\circ}$
- $30$ and $30^{\circ}$
- $30$ and $20^{\circ}$