<PRE><B>Question 1104010</B>
The diagonals of a rhombus are perpendicular to each other.  MRN is 90 degrees.
The sum of the interior angles of a polygon is (n-2)180, and this can be remembered by thinking of 3 sides, a triangle (180) and 4 sides (a square) of 360.
(n-2)(180)=900
n-2=5, n=7 sides
1980 degrees=(n-2)180
n-2=11, n=13 sides
5400 degrees=(n-2)180
n-2=30
n=32 sides
</PRE>