Find the Points on the Curve $x ( t ) = t ^ { 3 } - 9 t , y ( t ) = t ^ { 2 }$

Multiple Choice

Find the points on the curve $x ( t ) = t ^ { 3 } - 9 t , y ( t ) = t ^ { 2 }$ where the tangent line is vertical.

A) $( 6 \sqrt { 3 } , 3 )$
B) $( - 6 \sqrt { 3 } , 3 )$
C) $( - 6 \sqrt { 3 } , 3 \sqrt { 3 } )$
D) $( 6 \sqrt { 3 } , 3 \sqrt { 3 } )$
E) $( - 6 \sqrt { 3 } , 3 ) , ( 6 \sqrt { 3 } , 3 )$