If O is an angle in standard position and its terminal side passes through the point (2,-1), find the exact value of tan 0 in simplest radical form.

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?