Help me with these questions! Really, all I need to find out is the LSRL and the slope, and I can do the rest :) ASAP

What is the distance between point a and b

Acircle has a circumference of 7.850 units. what is its radius?

Sasha delivers newspapers to subscribers that live within a 4 block radius of her house. sasha's house is located at point (0, -1). points a, b, c, d, and e represent the houses of some of the subscribers to the newspaper. to which houses does sasha deliver newspapers?