--> //initializations

--> x=36 //degree (angle)
 x  = 

   36.


--> r3=100 //KN/m^2 (confining pressure)
 r3  = 

   100.


--> //calculations

--> r1=(r3*(1+sinm((x*%pi)/180)))/(1-sinm((x*%pi)/180)) // (pressure)
 r1  = 

   385.184


--> rd=r1-r3 //(deviator stress at failure)
 rd  = 

   285.184


--> //results

--> printf('deviator stress at failure=%f',rd) //KN/m^2
deviator stress at failure=285.184000
