In triangle ABC, we have:
∠A=40°,∠B=60°..(Given)
Here, ∠A+∠B+∠C=180°⇒60°+40°+∠C=180°⇒∠C=80°
∴ The side opposite to∠C, i.e., AB, is the longest side of triangle ABC.
Similarly, the side opposite to the smallest angle (∠A=40° ), i.e. BC is the smallest.