Question

Write the equation of a circle with a center at (0, 0) and a radius of 5.

Answer 1

(x-h) +(y - k) = r^2
equation of circle
where center is (h,k)
and r is radius
so replace h ,k and r by their values

Answer 2

The equation is (x-(x coordinate)) + (y-(y coordinate) = r^2

Answer 3

\(\bf (x-{\color{brown}{ h}})^2+(y-{\color{blue}{ k}})^2={\color{purple}{ r}}^2

\qquad center\ ({\color{brown}{ h}},{\color{blue}{ k}})\qquad
radius={\color{purple}{ r}}\)

plug in the given values

Answer 4

ok using jdoe's formula..... and your given information (0,0) r = 5

Answer 5

now let's start on the radius... that's easy... since r = 5. r^2 =?

Answer 6

25

Answer 7

yes!

Answer 8

ok... so the center is (x,y) which is (0,0) which is x = 0 and y = 0

Answer 9

\[\bf (x-{\color{brown}{ h}})^2+(y-{\color{blue}{ k}})^2={\color{purple}{ r}}^2 \qquad center\ ({\color{brown}{ h}},{\color{blue}{ k}})\qquad radius={\color{purple}{ r}}\]

sorry sorry I used the wrong letters it's center (h,k) h = 0 k = 0 x*(

Answer 10

from (0,0) we know that h = 0 and k = 0 so we can just plug those guys into the formula

Answer 11

\[(0-h)^2+(0-k)^2=25\]

Answer 12

no I made a mistake earlier... from (0,0) we know that h = 0 and k = 0 so we can just plug those guys into the formula

Answer 13

x and y should've been left alone... been dealing with that formula so much lol

Answer 14

\[(x-0)^2+(y-0)^2=25\]

Answer 15

yay. we're almost done. we just have to clean it up a bit x-0 = x and y-0 = y

Answer 16

so for this one....

Write the equation of a circle with a center at (1, 2) and a diameter of 15.

it would be.......

(x-1)^2 +(y-2)^2=15 ???

Answer 17

radius is half of diameter .....
r= d/2
r=radius
diameter =d

Answer 18

almost correct... the left is fine. you might have to solve for the radius on this one

Answer 19

so 7.5 ???

Answer 20

is my radius

Answer 21

yeah, but I would leave it as 15/2. teachers these days cringe on decimals.

Answer 22

lol true story

Answer 23

haha thanks you two :)