Question:
Find the centre and radius of each of the following circles :
$(x+5)^{2}+(y-3)^{2}=20$
Solution:
The general form of the equation of a circle is:
$(x-h)^{2}+(y-k)^{2}=r^{2}$
Where, (h, k) is the centre of the circle.
r is the radius of the circle
Comparing the given equation of circle with general form we get:
$h=-5, k=3, r^{2}=20$
$\Rightarrow$ centre $=(-5,3)$ and radius $=\sqrt{2} 0=2 \sqrt{5}$ units.
Ans: centre $=(-5,3)$ and radius $=2 \sqrt{5}$ units.
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