29.( 1)∫y = x+3 intersects with the x axis, and the y axis intersects with a, c, ∴ a (-3,0 0) C (0 0,3).

Vertex abscissa is -2, ∴ axis of symmetry straight line x=-2, from the symmetry, we can know that B (- 1, 0), ∴ let y=a(x+3)(x+ 1)(a≠0) and C (0)

(2) Vertex P(-2,-1), △PBD circumscribed circle radius

(3)2-