The radius r of the circle can be calculated using the distance between two-point formula
[tex]\begin{gathered} r\text{ = }\sqrt[]{x_2-x_1)^2+(y_2-y_1)^2} \\ x_1=11,y_1=-3x_2=3,y_2=12\text{ } \\ \\ r=\sqrt[]{(3-11)^2+(12-(-3))^2} \\ \\ r=\sqrt[]{(-8)^2+(15)^2} \\ r=\sqrt[]{64+225} \\ r=\sqrt[]{289} \\ r=17\text{ unit} \end{gathered}[/tex]
