cos(α-β) = cosαcosβ + sinαsinβ

Therefore, the expression sinαsinβ + cosαcosβ - cos(α-β) simplifies to:

sinαsinβ + cosαcosβ - (cosαcosβ + sinαsinβ)

Simplifying further:

sinαsinβ + cosαcosβ - cosαcosβ - sinαsinβ
= cosαcosβ - cosαcosβ
= 0

Therefore, the final answer is 0.