Answer:
Step-by-step explanation:
cos (2α)*sin (α-β)-cos(β-α)*sin(2α)cos (β-α)=cos {-(α-β)}=cos (α-β)
[cos (-x)=cos x]
sin(α-β)*cos (2α)-cos (α-β)*sin (2α)=sin (α-β-2α)=sin (-α-β)
=sin {-(α+β)}
=-sin (α+β)
