Mild steel is being machined at a cutting speed of 200 m/min with a tool of rake 10^o. The depth of cut and uncut thickness are 2 mm and 0.2 mm, respectively.  Average value of the coefficient of friction between tool and chip is 0.5 and shear stress `tau_s`of the work material is 400 N/mm².  Use 2`phi+lambda-alpha`  = 90^o.

The shear angle is