In triangle ABC, if $\angle A=50°,\angle B=60°$, then the greatest side is

Using angle sum property of triangle

∠A+∠B+∠C=180$°$

Or, $50°+60°$+∠C=$180°$

Or,∠C=$180°-110°=70°$

The side opposite the largest angle is the longest side.

Here ∠C is the largest and the side opposite it is AB

So AB is the longest side.