Find the points on the curve where the tangent is horizontal or vertical. You may want to use a graph from a calculator or computer to check your work. (If an answer does not exist, enter DNE.) x = t' - 3t, y = tz - 5 horizontal tangent (x, y) = 0, - 8 X vertical tangent (smaller x-value) ( x, y ) = vertical tangent (larger x-value) ( x, y ) =