Question

Find the standard equation of the circle that satisfies the conditions.

Center (-1,-3), passing through the point (3,0)

Answer 1

`Equation\ of\ circle\\\\\ r^2=(x-a)^2+(y-b)^2\\\\ a,b- \ coordinates\ of\ center\ of\ circle\\\\\ (a,b)=(-1,-3)\\\\ r^2=(x+1)^2+(y+3)^2\\\\\ Substituting\ point\ (3,0)\\\\ r^2=(3+1)^2+(0+3)^2\\\\ r^2=4^2+3^2\\\\ r^2=16+9=25\\ r=5\\\\ Answer:\ \ 25=(x+1)^2+(y+3)^2`