Question

Write a standard equation for the circle below.

Answer 1

start by finding its "center" and "radius"

Answer 2

well, there are 2 circles there

Answer 3

but in short -> http://www.mathwarehouse.com/geometry/circle/images/equation-of-circle/example-2-equation-of-circle.png

Answer 4

it wants P

Answer 5

center is (-4,1)

Answer 6

how do i find radius?

Answer 7

Yes, wat about radius

Answer 8

radius is the distance from "center" to "any point on the circle"

Answer 9

oh ok
so i could use (-2,5)

Answer 10

nope. we dont knw if that point lies on the circle or not.
but u can use below point :
(0, 2)

Answer 11

btw, the center should be :
(-4, 2)

Answer 12

so it doesnt have to lie on the circle?

Answer 13

the point has to lie on circle

(0, 2) lies on circle... (it is on the blue curve)

Answer 14

i see it is going by increments of 2 lol oh ok

Answer 15

yes, i also noticed it very late lol

Answer 16

so you have :
center = (-4, 2)

Answer 17

radius = ?

Answer 18

(x-h)^2+(y-k)^2=r^2

Answer 19

yes thats the standard equation of circle

Answer 20

(x--4)^2+(y-2)^2=r^2
(0+4)^2+(-2-2)^2=r^2
4^2+0^2=r^2


like that ?

Answer 21

that wil do, so r = 4 ?

Answer 22

16=r^2
4=r

Answer 23

u can make that out from the given diagram also.
the circle is 2 grids away from its center !
so radius = 4 units

Answer 24

either way it wil work

Answer 25

finally u have both center and radius :
center = (h, k) = (-4, 2)
radius = r = 4

Answer 26

setup the equation

Answer 27

(0+4)^2+(2-2)^2=4^2

Answer 28

nope ! leave the x and y as-it-is

Answer 29

(x-h)^2 + (y-k)^2 = r^2

plugin h, k, r values

Answer 30

dang (x-4)^2+(y-2)^2=4^2

Answer 31

:) bit still a silly mistake is there...
try again

Answer 32

i know its ( x+4)^2+(y-2)^2=4^2

Answer 33

Yup !!! good job !

Answer 34

i forgot double negative :)

Answer 35

ty @jdoe0001 @ganeshie8

Answer 36

hahah happens (:

Answer 37

u wlc !