2013 ... 5 & 6

This first one looks weird, but it's just triangles. The second is good old number theory..

"Simple" area.

Difficulty: relatively easy, but again, many students stumbled on it.

Difficulty: Easy.

Standard instructions for this series: No calculator allowed. Express answers in reduced form. Rationalize denominators. Radicals must be reduced. All numbers are base ten unless otherwise specified. Do not approximate radicals or π. Leave such answers as 1025π or √39, for example. Source: UVM Math Contest 2013

answer 05, answer 06.