So I've got this problem that is making me go a little insane, I'm not sure if I'm just missing simple identities or what. The diagrams and the problem are shown below.
I hope someone can give insight into how to do these few problems. We are given Ptolemy's Theorem for quadrilaterals,
$AB\times CD + BC\times AD=120BD$
Where the diameter of the circle in which the quadrilateral is inscribed is $120$, in other words, $AC=120,$ in Ptolemy's words.
I've already tried a couple things, but I've gotten stuck going down the plug-in-and-see-what-happens rabbit hole.
Thanks!