Question

please help
Write the standard equation for the circle that passes through the points (- 5, 0), (0, 4), and (2, 4)

Answer 1

assume a general eq x^2 + y^2 + 2gx + 2fy + c = 0
g , f , c are unknowns and 3 conditions/ points are given

so can you find out g, f and c?

Answer 2

4x^2+4y^2-79/16x+95/8-2y
but its wrong

Answer 3

@harsimran_hs4

Answer 4

A full answer with graph can be found here:
http://www.wolframalpha.com/input/?i=Equ …

So how do you set it up? (x–h) ² + (y–k)² = r² we have 3 unknowns and need to solve for h, k and r. Just plug in the three points one at a time and get:

(–5–h)² + (0– k)² = r² → h²+10h + 25 + k² = r²

(0–h)² + (4– k)² = r² → h² +k² –8k + 16 = r²

(2–h)² + (4– k)² = r² → h² – 4h + 4 + k² –8k + 16= r²

All of these reduce to:

h²+10h + 25 + k² = r²
h² +k² –8k + 16 = r²
h² – 4h + k² –8k + 20= r²

If you solve the system (not a trivial task), you will get

(x-1)²+(y+19/8)² = 2665/64

Answer 5

so you can have a look at the above solution
if still any confusion you can ask

Answer 6

these three ar my unknowns -79/16x+95/8-2y

Answer 7

@dusty how can i find the final answer?

Answer 8

@begzat when you solved what values did you get for g, f, c?

Answer 9

-79/16x + 95/8 -2y this are my solution that i get

Answer 10

how come x comes in ?
g = ?
f = ?
c = ?

can you fill the blanks?

Answer 11

no

Answer 12

then perhaps you should first have a look at dusty`s post
look at it line by line and try to figure out
he has taken the general eq in another form

Answer 13

hey im a girl lol :)

Answer 14

im stock i have no idea

Answer 15

@dusty i apologize for it

Answer 16

its okay :)

Answer 17

are this wrong for these points -79/16x + 95/8 -2y or not

Answer 18

i mean the answer its wrong

Answer 19

@dusty can you solve for me please

Answer 20

why dont you do this one :)
equation of circle is
(x-a)^2 +(y-b)^2 = r^2
substitute
A(- 5, 0)
B(0, 4)
C(2, 4)
into circle equation and you get a system of 3 equation in a,b, r an find center and radius

Answer 21

do you understand stand?

Answer 22

so i have to take just one of the points

Answer 23

go to this link it will help you.
http://www.wolframalpha.com/input/?i=Write+the+standard+equation+for+the+circle+that+passes+through+the+points+%28-+5%2C+0%29%2C+%280%2C+4%29%2C+and+%282%2C+4%29

Answer 24

(5 - 2)^2 + (4 - 0)^2 = r^2

3^2 + 4^2 = r^2

9 + 16 = r^2

25 = r^2

r = 5

Answer 25

x^2+y^2-4x-25 = 0
is this final answer