All sides are congruent. 5. Is this figure a polygon?
Answer the questions below only if the figure is a polygon.
la. Is this polygon concave or convex?
1b. Is this polygon regular, equiangular, equilateral, or none of these?
1c. What is the name of this polygon?

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.