We need to find the equation of the circle using the next equation:
![x^2+y^2+8x-2y-13=0](https://img.qammunity.org/2023/formulas/mathematics/college/yi0itgpplakl9j0rjqqcx8irnfhch96veb.png)
Then:
![x^2+8x+y^2-2y=13](https://img.qammunity.org/2023/formulas/mathematics/college/kqv5w2rrowdzgqbswhlxyfhfdnuy9hsbny.png)
Now, we need to complete the squares :
![\begin{gathered} x^2+8x+16=(x^2+4)^2 \\ and \\ x^2-2y+1=(x^2-1)^2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/jj579eu4no1k8y0mo6dpr6wvvpvnc13rqn.png)
Then, we have the next expression:
![\begin{gathered} x^2+8x+16+y^2-2y+1=13+16+1 \\ Simplofy: \\ (x^+4)^2+(y-1)^2=30 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/jrn7cus1gtr1o0t0kfwe8zck1c85vq0qkz.png)
We have the form (x-h)² + (y-k)²=r²
Where (h,k) is the center and r represents the radius.
Now, the center is (-4,1)
and the radius is √30 = 5.47....