If PQis a focal chord, show that the interval RU is parallel to the axis of the parabola. ![enter image description here]( For part (c) of question thirteen am I only required to find the gradient of RU and prove tha...--prophetes.ai

If PQis a focal chord, show that the interval RU is parallel to the axis of the parabola. ![enter image description here]( For part (c) of question thirteen am I only required to find the gradient of RU and prove that is it zero? This is how I have interpreted this question. ANY help on the matter is much appreciated thank you in advance.

hint...The focal chord property is $pq=-1$, whereupon you can calculate the gradient of $RU$...