Answer:
[tex]p = \sqrt{sn + a^{2} }[/tex]
Step-by-step explanation:
[tex]\frac{p^{2} - a^{2} }{n} = s[/tex] multiply by n on both sides
[tex]p^{2} - a^{2} = sn[/tex] add [tex]a^{2}[/tex] on both sides
[tex]p^{2} = sn +a^{2}[/tex] take a square root on both sides
[tex]p = \sqrt{sn + a^{2} }[/tex]