If Dave is standing next to a silo of cross-sectional radius
r = 9
feet at the indicated position, his vision will be partiallyobstructed. Find the portion of the y-axis that Davecannot see. (Hint: Let a be the x-coordinate ofthe point where line of sight #1 is tangent to the silo; computethe slope of the line using two points (the tangent point and (12,0)). On the other hand, compute the slope of line of sight #1 bynoting it is perpendicular to a radial line through the tangencypoint. Set these two calculations of the slope equal and solve fora. Enter your answer using interval notation. Round youranswer to three decimal places.)
