Question

HELP:
What is the general form of the equation for the given circle?

x2 + y2 − 8x − 8y + 23 = 0

x2 + y2 − 8x − 8y + 32 = 0

x2 + y2 − 4x − 4y + 23 = 0

x2 + y2 + 4x + 4y + 9 = 0

Answer 1

http://cdn.ple.platoweb.com/PCAP-ASSETS-PROD/03974c930e3e47c78f1614a92ab2c070

Answer 2

you could do this by plugging in the given values of x and y which are on the circle and see which option fits

Answer 3

for example try point A = (4,7) on first option

left side of the equation = 4^2 + 7^2 - 8(4) - 8(7) + 23 = 0

so that satisfies the equation
but now we have to try the other point (7,4)

if that gives 0 then we have the correct equation

Answer 4

what does
7^2 + 4^2 - 8(7) - 8(4) + 23 work out to?

Answer 5

@bruno101?

Answer 6

- compare it with my first post...

Answer 7

* second post

Answer 8

does that work out to zero?

Answer 9

yes your right if u plug in the other point (7,4) u get 0 as your final answer

Answer 10

yes you do
so that is the required equation
because it satisfies the 2 points (4,7) and (7,4)

Answer 11

first option is the one

Answer 12

so its A

Answer 13

yea

Answer 14

and your right thanks for the help!

Answer 15

yw