With her almond-shaped eyes and earthy intensity, Alexander possesses a disarmingly composed manner that often makes the characters she play appear more secure than they really are. Before nabbing the role of the calculating Maxine Shaw on the Fox sitcom "Living Single" (1993-97), Alexander made her TV series debut as Clair Huxtable's (Phylicia Rashad) 17-year-old less-privileged second cousin Pam on the last two seasons of "The Cosby Show" (NBC, 1990-1992). When that show's run ended, she showed up the following season as the proud but insecure medical student Cheryl Carter on the short-lived