Z twierdzenia sinusów:

$\frac{b}{\sin \beta }=\frac{c}{\sin \gamma }$

$\frac{b}{c}=\frac{\sin \beta }{\sin \gamma }$   

A.Prawda

Z twierdzenia sinusów:

$\frac{a}{\sin \alpha }=\frac{c}{\sin \gamma }$  

$\frac{a}{c}=\frac{\sin {30}^o}{\sin \gamma }$  

$\frac{a}{c}=\frac{\frac{1}{2}}{\sin \gamma }$  

$\frac{a}{c}=\frac{1}{2\sin \gamma }$  

B. Fałsz

 

$a$ /sinalpha = 2R 

$\frac{a}{\sin {30}^o}=2R$  

$\frac{a}{\frac{1}{2}}=2R$  

$2a=2R$  

$a=R$  

C. Prawda