Distance from center of 1900 sq feet square to corners is about 31 feet, isn't it?
Range of wireless access point (WAP) indoors is probably 100 feet or more (depending on how thick the walls are).
However, wireless connection has two players: the WAP and the WiFi client device (your laptop, phone, etc).
The effective range is the range of the weaker party, WAP or client.
Similarly, when you have more than one WAP that all advertise the same wireless network, it is up to the client device whether it switches (roams) from currently connected WAP to stronger signal WAP. The WAPs can merely give cues, like cut weak connections (they assume that client is closer to some other WAP).