cos (A - B) = cos A cos B + sin A sin B
If true then write 1 and if false then write 0
Given, A=60∘ and B=30∘
Now, cos(A−B)=cosAcosB+sinAsinB
L.H.S : cos(A−B)=cos(600−300)=cos300=√32
R.H.S: cosAcosB+sinAsinB=cos600cos300+sin600sin300
= (12)(√32)+(√32)(12)
= √34+√34
= √32
∴LHS=RHS
∴cos(A−B)=cosAcosB+sinAsinB