To answer this question we need to remember that:
In this case this means that:
[tex]PB^2=PA(PA+AC)[/tex]
Plugging the values given we have:
[tex]\begin{gathered} PB^2=(5)(5+15) \\ PB^2=100 \\ PB=\sqrt{100} \\ PB=10 \end{gathered}[/tex]
Therefore, the length of PB is 10 and the asnwer is b.
