The general form of equation of circle is :
[tex]\begin{gathered} (x-a)^2+(y-b)^2=r^2 \\ \text{where, (a,b) are the center and r is the radius} \end{gathered}[/tex]
Given system of equation:
[tex](x+10)^2+(y-7)^2=16[/tex]
Simplify it into the general form
[tex]\begin{gathered} (x+10)^2+(y-7)^2=16 \\ (x-(-10))^2+(y-7)^2=4^2 \end{gathered}[/tex]
On comparing with the general form we get
a = -10, b = 7, r = 4
Thus, radius = 4
Answer: D) 4
