suppose that, as in exercises 5.11 and 5.79, y1 and y2 are uniformly distributed over the triangle shaded in the accompanying diagram. (–1, 0) (1, 0) (0, 1) y1 y2 a find cov(y1, y2). b are y1 and y2 independent? (see exercise 5.55.) c find the coefficient of correlation for y1 and y2. d does your answer to part (b) lead you to doubt your answer to part (a)? why or why not?