Question

What is the radius of a circle whose equation is (x + 5)^2 + (y – 3)^2 = 4^2? What are the coordinates of the center of the circle?

Answer 1

`\textit{equation of a circle}\\\\ (x- h)^2+(y- k)^2= r^2 \hspace{5em}\stackrel{center}{(\underset{}{h}~~,~~\underset{}{k})}\qquad \stackrel{radius}{\underset{}{r}} \\\\[-0.35em] ~\dotfill\\\\ (x+5)^2+(y-3)^2=4^2\implies ( ~~ x-(\stackrel{ h }{-5}) ~~ )^2+(y-\stackrel{ k }{3})^2=\stackrel{ r }{4^2}\qquad \begin{cases} \stackrel{ center }{(-5,3)}\\ \stackrel{radius}{4} \end{cases}`