$\text{I.}$

${\left|\text{PO}\right|}^2={\text{r}}^2+{\left|\text{PA}\right|}^2$

$5^2=3^2+{\left|\text{PA}\right|}^2$

${\left|\text{PA}\right|}^2=25-9$

${\left|\text{PA}\right|}^2=16$

$\left|\text{PA}\right|=4$

$\text{Pole:}$

$\text{P}=\frac{1}{2}\cdot 3\cdot 4=6{\text{cm}}^2$

$\text{Odp: A.}$

 

$\text{II.}$

${180}^o-{90}^o-{20}^o={70}^o$