The height of the new bike tunnel, y, in feet, is given by the following equation, where x is the horizontal distance, in feet, from the center line of the opening of the tunnel. y=-x^2+36 Note that negative x-values indicate the distance to the left of the center line, and positive x-values indicate the distance to the right of the center line. Plot the points on the graph where the height of the tunnel is a maximum and where the height of the tunnel is zero feet.