Question

What is the equation of the graph illustrated below?

http://curriculum.kcdistancelearning.com/courses/GEOMx-HS-A09/b/assessments/C-CirclesExam/Geometry_7_Exam_79q.gif

Answer 1

@amistre64 @myininaya please i really need help

Answer 2

pfft, you know this. all we need is a center and a radius. what would you propose they are?

Answer 3

0, 2 and 4?

Answer 4

correct,

now, how do we find the distance between 2 points? (x,y) and (0,2)?

Answer 5

im not sure...

Answer 6

theres a phrase im thinking of, starts with 'distance' and ends with 'formula' ... what would that be?

Answer 7

http://www.mathwarehouse.com/algebra/distance_formula/images/distance-formula4.png

Answer 8

i looked up distance formula :)

Answer 9

i circle is defined as the distance of all points (x,y) from a center point.

:) so give it your best shot, how can we fill out that formula?

Answer 10

plug in x and y?

Answer 11

it may be better if we notate it like this from some distance,d, and some center point (cx,cy)
\[d=\sqrt{(x-c_x)^2+(y-c_y)^2}\]

the equation of a circle is actually the square of d so ... lets rewrite it as:
\[d^2=(x-c_x)^2+(y-c_y)^2\]

Answer 12

ok...

Answer 13

@amistre64

Answer 14

we know d, and cx, cy .... fill em in

Answer 15

ok hold on...

Answer 16

@amistre64 what do i do when i plug them in?

Answer 17

well since we are looking for the equation of the circle, and the equation is such that:\[d^2=(x-c_x)^2+(y=c_y)^2\]
i would say that if there is any simplification to do ... cleaning up any zero sums .... then thats all there is to do.