Coverage is an important performance metric for wireless sensor networks (WSNs), and different coverage models have been proposed for different WSN applications. In this paper, based on the confident information coverage (CIC) model proposed in our previous study, we study the critical sensor densities (CSDs) of three simple placement patterns, which are tiling by repeating three regular polygons, namely, the regular triangle, square, and hexagon, respectively. We first prove that if the center point of such a polygon can be confident information covered, then all the space points within the polygon can also be confident information covered by the sensors located at the vertices of the polygon. Based on this result, we then compute the largest side lengths of three regular polygons for different coverage requirements. Finally, we compare the CSDs of three simple placement patterns for different coverage and connectivity requirements.