Question

The equation (x - 1)² + (y - 3)² = 12 represents circle A.The point (4, 7) lies on circle A.What is the length of the radius of circle A?O V135O 575O 137

Answer 1

`\begin{gathered} \text{The point }(4,7)\text{ represents a }(x,y)\text{ coordinate thus, we can substitute the values to the} \\ \text{equation of the circle},\text{ to solve for radius }r \\ (x-1)^2+(y-3)^2=r^2 \\ (4-1)^2+(7-3)^2=r^2 \\ (3)^2+(4)^2=r^2 \\ 9+16=r^2 \\ 25=r^2 \\ \sqrt[]{25}=\sqrt[]{r^2} \\ r=5 \\ \text{Therefore, the length of the radius of circle A is }5\text{ units.} \end{gathered}`