# c1- circlesWatch

#1
how do i do this question?

x^2+y^2-6y-7=0
0
4 years ago
#2
(Original post by longsightdon)
how do i do this question?

x^2+y^2-6y-7=0
???? do what ???
0
#3
(Original post by TeeEm)
???? do what ???
oooops find the coordinates of the centre of the circle
0
4 years ago
#4
(Original post by longsightdon)
oooops find the coordinates of the centre of the circle
complete the square in x and in y, then you read it off. I am sure your teacher must have shown you this
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#5
(Original post by TeeEm)
complete the square in x and in y, then you read it off. I am sure your teacher must have shown you this
but there is only a x^2 and no other x in the equation
0
4 years ago
#6
(Original post by longsightdon)
but there is only a x^2 and no other x in the equation
even better ...

then x2 =(x-0)2, and you should know what that means for a circle.
0
#7
(Original post by TeeEm)
even better ...

then x2 =(x-0)2, and you should know what that means for a circle.
what does that mean?
0
4 years ago
#8
(Original post by longsightdon)
what does that mean?
For instance

(x-2)2+(y+7)2=49 represents a circle centre at (2,-7) radius root(49)=7

then you should be able to work your out
0
#9
(Original post by TeeEm)
For instance

(x-2)2+(y+7)2=49 represents a circle centre at (2,-7) radius root(49)=7

then you should be able to work your out
oh i see thanks
0
4 years ago
#10
(Original post by longsightdon)
oh i see thanks
pleasure
0
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