The coordinate of ∵C is (2,3.5),

∫B is higher than the ground 1.5m,

The coordinate of ∴B is (0, 1.5),

Substitute it into a parabola:

The analytical formula of parabola is y=- 12(x-2)2+72 or y =-12x2+2x+32;

(2) The inclination angle α = 27,

Let the coordinate of a point on the straight line where the slope is located be (x, y),

So y=x? tan27，

That is, the linear equation of slope OA is y = x2.

(3) y = 12xy =？ 12x2+2x+32，

Solution: x≈3.8y≈ 1.9,

OA≈4.2 meters,

A: The longest distance of water flow on the hillside is about 4.2 meters.