Question

C(4, -7). Calcule o raio dessa circunferência, sabendo que ela passa pelo ponto A(-5, 5).

Answer 1

$\displaystyle \underline{\text{Equa{\~a}o da circunfer{\^e}ncia}}: \\\\ (\text x-\text x_c)^2+(\text y-\text y_\text c)^2=\text R^2 \\\\ \underline{\text{Centro C(4, -7)}}: \\\\ (\text x-4)^2+(\text y+7)^2=\text R^2 \\\\ \text{Para acha o raio basta substituir o ponto A(-5,5)} : \\\\ (-5-4)^2+(5+7)^2 = \text R^2 \\\\ (-9)^2+(12)^2=\text R^2 \\\\ 81+144=\text R^2 \\\\ \text R^2 = 225 \\\\ \huge\boxed{\ \text R = 15\ }\checkmark$