Ah, but I'm just following the logic from the question, as follows:
(i) Show that tangential accleration of P is given by:
s'' = l(d/dø)(1/2 * w<sup>2</sup>)
where s is arc length
(ii) Show that the equation of motion of the pendulum is
l(d/dø)(1/2 * w<sup>2</sup>) = -gsinø
Sure, I would love...