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Circles question (1 Viewer)

skillz

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HSC
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Find the radii and coordinates of the centre of the circles with equations
4x^2+4y^2-60x-76y+536=0 and x^2+y^2-10x-14y+49=0 and find the coordinates of the point of intersection of the two curves.

I've got the two equations in this form.
(x-15/2)^2+(y-19/2)^2 and radius 5root2/2
and
(x-5)^2+(y-7)^2 and radius 5

now how do i find the points of intersection?

2)
another question.find the co ordinates of the points of intersection with x^2+y^2=25 and the line with y=x and y=2x.
im guessing its the same principle but i don't know how to do the first question..

thanks alot guys.
 

Mountain.Dew

Magician, and Lawyer.
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Sydney, Australia
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2005
skillz said:
Find the radii and coordinates of the centre of the circles with equations
4x^2+4y^2-60x-76y+536=0 and x^2+y^2-10x-14y+49=0 and find the coordinates of the point of intersection of the two curves.

I've got the two equations in this form.
(x-15/2)^2+(y-19/2)^2 and radius 5root2/2
and
(x-5)^2+(y-7)^2 and radius 5

now how do i find the points of intersection?

2)
another question.find the co ordinates of the points of intersection with x^2+y^2=25 and the line with y=x and y=2x.
im guessing its the same principle but i don't know how to do the first question..

thanks alot guys.
do simulatenous equations ==> method 1: for ONE equation, get either x or y as the subject, then substitute that x or y into the OTHER equation to get an equation all in terms of x or y. then, solve for that single variable. then, with the value of ur variable, sub that back into the original equation to get the value of the other variable.

method 2: elimination ==> getting rid of certain variables, like x^2 and y^2 via subtraction of both equations to get a new equation that is easier to manipulate for substitution back into original equations.

applies for both questions.

if still have some problems, please reply or PM me.
 
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