+278 There is LaTeX so some of it may appear missing when reading it on the forum but it's there when you click on it.
Let \(ABCD\) be a convex quadrilateral, and let \(M\) and \(N\) be the midpoints of sides \(\overline{AD}\) and \(\overline{BC} \), respectively. Prove that \(MN \le (AB+CD)/2 \). When does equality occur?
I was also given a hint: Let \(P\) be the midpoint of diagonal \(\overline{BD }\). What does the triangle inequality tell you about triangle \(MNP \)?
