Question

What is the general form of the equation of a circle with its center at (-2, 1) and passing through (-4, 1)?

Answer 1

`(x+2)^2+(y-1)^2=4`

Explanation:

`"first ; let's find the radius of circle:"`
`"Center: "(-2,1)`
`"Point: "(-4,1)`
`Delta x"=Point(x)-Center(x)"`
`Delta x=-4+2=-2`
`Delta y"=Point(y)-Center(y)"`
`Delta y=1-1=0`
`r=sqrt(Delta x^2+Delta y^2)`
`r=sqrt((-2)^2+0)`
`r=2" radius"`

`"now ; we can write the equation"`
`C(a,b)" center's coordinates"`
`(x-a)^2+(y-b)^2=r^2`

`(x+2)^2+(y-1)^2=2^2`

`(x+2)^2+(y-1)^2=4`