Author Topic: 2 Simple Questions!  (Read 2750 times)

Offline SGVaibhav

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2 Simple Questions!
« on: January 11, 2010, 05:35:17 am »
1) Solve the following inequality :             
|x-2|>1

2) Find the equation of the circle that passes through (0,1) (2,0) (3,4)

Offline astarmathsandphysics

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Re: 2 Simple Questions!
« Reply #1 on: January 11, 2010, 08:39:59 am »
When I get up

Offline SGVaibhav

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Re: 2 Simple Questions!
« Reply #2 on: January 11, 2010, 08:46:28 am »
u wrote the reply in dreams or while sleeping (sleep writing / sleep posting?)
lool

Offline astarmathsandphysics

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Re: 2 Simple Questions!
« Reply #3 on: January 11, 2010, 08:50:27 am »
Yes I was sleep posting

Offline astarmathsandphysics

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Re: 2 Simple Questions!
« Reply #4 on: January 11, 2010, 09:46:40 am »
1) Solve the following inequality :             
|x-2|>1

2) Find the equation of the circle that passes through (0,1) (2,0) (3,4)

) Solve
x-2>1 and x-2<-1
x>3 or x<1
2)The equation of a circle is given by
x^2+y^2+ax+by=c
Sub each point in and solve the simultaneous equations
1+b+c=0(1)
4+2a+c=0(2)
25+3a+4b+c=0(3)
(2)-(1) 3+2a-b=0 (4)
(3)-(1)24+3a+3c=0 so 8+a+b=0 (5)
(4)+(5) 11+3a=0 so a=-3/11
then from (5)8-3/11+b=0 so b=-85/3
Then from (1) 1-85/3+c=0 so c=82 over 3
x^2+y^2-3x/11-85y/3+82/3=0


Offline SGVaibhav

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Re: 2 Simple Questions!
« Reply #5 on: January 11, 2010, 09:52:58 am »
understood everything EXCEPT, what do u do after finding a, b and c in the 2nd question.

Offline astarmathsandphysics

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Re: 2 Simple Questions!
« Reply #6 on: January 11, 2010, 10:51:43 am »
sub them into th e formula for the circle x^2+y^2+ax+by=c

Offline SGVaibhav

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Re: 2 Simple Questions!
« Reply #7 on: January 11, 2010, 03:28:46 pm »
so how do we then get the center and radius, i forgot ???

Offline astarmathsandphysics

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Re: 2 Simple Questions!
« Reply #8 on: January 11, 2010, 03:50:06 pm »
Complete the square. Will do it proper when I get home

Offline SGVaibhav

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Re: 2 Simple Questions!
« Reply #9 on: January 11, 2010, 04:39:28 pm »
oh yeah, i found out something...

i got another method, it says Centre = (-A/2  , -B/2)    (i dont know if its right)
                                    and radius = Square root of ( (-a/2)^2  +   (-b/2)^2   - c))     [square root of   -a/2 square + -b/2 square - c]

Offline astarmathsandphysics

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Re: 2 Simple Questions!
« Reply #10 on: January 11, 2010, 08:06:12 pm »
Yes that is true