List all of the points (r,θ)(r,θ) where the tangent line is horizontal. in entering your answer, list the points starting with the smallest value of rr and limit yourself to 1≤r≤10001≤r≤1000 ( note the restriction on rr! ) and 0≤θ< 2π.0≤θ< 2π. if two or more points share the same value of rr, list those starting with the smallest value of θ.θ. if any blanks are unused, type an upper-case "n" in them.