Q

Find the centre and radius of the circles. x^2 + y ^2 - 4x - 8y 45 equal = 0

7.  Find the centre and radius of the circles.

$x^2 + y^2 -4x - 8y - 45 = 0$

Views

As we know,

The equation of the circle with centre ( h, k) and radius r is given by ;

$(x-h)^2+(y-k)^2=r^2$

Given here

$x^2 + y^2 -4x - 8y - 45 = 0$

Can also be written in the form

$(x-2)^2 + (y-4)^2 =(\sqrt{65})^2$

So, from comparing, we can see that

$r=\sqrt{65}$

Hence the Radius of the circle is $\sqrt{65}$.

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