**Half the angle of nip, (α), for a roll crusher is given by (where, dr, dp and df are diameters of crushing rolls, feed particles and rolls gap respectively) ?**

**A. cos α = (dr + dp)/(dr + df)**

B. cos α = (dr + df)/(dr + dp)

C. tan α = (dr + dp)/(dr + df)

D. sin α = (dr + dp)/(dr + df)