Please help! I will medal! Thanx! :)
Which is the equation of a circle with center (-2,3) and radius r=5?
a. (x+2)^2 + (y-3)^2= 10
b. (x+2)^2 + (y-3)^2= 25
c. (x-2)^2 + (y+3)^2= 10
d. (x-2)^2 + (y+3)^2=25

Question

Please help! I will medal! Thanx! :)
Which is the equation of a circle with center (-2,3) and radius r=5?
a. (x+2)^2 + (y-3)^2= 10
b. (x+2)^2 + (y-3)^2= 25
c. (x-2)^2 + (y+3)^2= 10
d. (x-2)^2 + (y+3)^2=25

anonymous · Answer

@raiders88

anonymous · Answer

@kelliegirl33

anonymous · Answer

oh thanks!

nnesha · Answer

$$\huge\rm (x-h)^2 + (y-k)^2 = r^2$$
equation of circle in standard form 
where ( h,k) is the center and r is radius 
just replace variables by their values

anonymous · Answer

so would i put (x+2)^2 = (y-3^)2= for the equation?how would i get the ending answer?

nnesha · Answer

r=5
what is r^2 = ?

anonymous · Answer

25

anonymous · Answer

so it would be B then?

anonymous · Answer

thank you!

nnesha · Answer

great !! :-)

nnesha · Answer

my pleasure :-)

anonymous · Answer

could you help me with a few more?

nnesha · Answer

i'll try :-)

anonymous · Answer

thx :) i'll post the next one on here hang on :)

nnesha · Answer

okay

anonymous · Answer

A circle with center (-1,2) passes through point (2,-2). Which is true?
a. the radius is sqrt5
b. the diameter is 10
c. the equation is (x+1)^2 + (y-2)^2= 10
d. the circumference is 25pi

nnesha · Answer

okay now again circle is (h,k) points 
passing through (x , y) 
so replace x and y by (2,-2) and (h,k) by (-1,2)
then solve for r

nnesha · Answer

same equation $$\huge\rm (x-h)^2 + (y-k)^2 = r^2$$

anonymous · Answer

how would i solve for r after i get the equation?

anonymous · Answer

so i got (2-(-1)^2 + (-2 - 2)^2 then i solved and got 9 + 16 = 25

nnesha · Answer

same equation $$\huge\rm (\color{green}{x}-\color{blue}{h})^2 + (\color{red}{y}-\color{gold}{k})^2 = r^2$$
 $$\huge\rm  (\color{green}{2},\color{red}{-2})$$
   $$\huge\rm (\color{blue}{-1},\color{gold}{2})$$
plug in x,y,h,k values

anonymous · Answer

so would the answer be either a or d right?

anonymous · Answer

i think the answer is a

nnesha · Answer

ohhh

anonymous · Answer

but then again the square root of 5 is 2.24 so that isn't correct.

nnesha · Answer

r^2 = 16+9
r^2 = 25
to solve for r you should take square root both side 
so $$\huge\rm \sqrt{r^2}= \sqrt{25}$$
r= ?

anonymous · Answer

the square root of 5 is correct then!

anonymous · Answer

right?

nnesha · Answer

|dw:1431552141446:dw|
25 is perfect square root  which is equal to 5

nnesha · Answer

|dw:1431552191916:dw|
hint :radius is half of diameter