Question

Write the equation of a circle with center at (4, 1) and a radius of 6.
A. (x - 4)2 + (y – 1)2 = 36
B. (x + 4)2 + (y + 1)2 = 36
C. (x - 4)2 + (y – 1)2 = 6
D. (x + 4)2 + (y + 1)2 = 6

Answer 1

@robz8 how did you get that last one? i totally forgot to ask.

Answer 2

okay well your center is (4, 1) where x = 4 and y = 1

so when you look at these choices, your parenthesis need to equal 0

so you're looking for (x-4) and (y-1) because (4-4) and (1-1) both equal 0

and all that = r^2

so your radius is 6

so your equation needs to equal 36

looks like A to me

Answer 3

\[\Huge (x-h)^2+(y-x)^2=a^2\]
is the equation of the circle

Answer 4

Write the equation of a circle with center at (0, 0) and a diameter of 20.

okay so for this one, is it just 20 since the center is 0, 0 ??

Answer 5

\[\Huge x^2+y^2=a^2\]

Answer 6

since -h and -k are 0

Answer 7

^

Answer 8

@chicagoblkhaks since your DIAMETER is 20, your radius would be 10

and remember, it equals the radius SQUARED

to it would just be x^2 + y^2 = 100

since (x-0)^2 + (x-0)^2 = 10^2

Answer 9

@DLS a little typo in your first equation btw :P

Answer 10

oh lol sorry

Answer 11

ohh. i knew that. hah. oops. 20 isnt even an option for me, i just typed it i guess thinking about the diameter. ugh. embarrassing