Question

What is the equation of a circle with center (2, -5) and radius 4?

Answer 1

$Equation\ of\ circle\\\\\ r^2=(x-a)^2+(y-b)^2\\\\ a,b- \ coordinates\ of\ center\ of\ circle\\\\\ (a,b)=(2,-5) \\\\ r-\ radius\\\\ r=4\\\\Solution:\ 4^2=(x-2)^2+(y+5)^2$

Answer 2

$(x-h)^2+(y-k)^2=r^2\\\\ (x-2)^2+(y+5)^2=16$