Find the centre and radius of each of the following circles : (x + 5)2

1.	Find the centre and radius of each of the following circles : (x + 5)2 + (y – 3)2 = 20
Answer» The general form of the equation of a circle is: (x - h)² + (y - k)² = r² 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, r² = 20 ⇒ centre = ( - 5, 3) and radius = √20 = 2√5 units. Ans: centre = ( - 5, 3) and radius = 2√5 units.

Find the centre and radius of each of the following circles : (x + 5)2 + (y – 3)2 = 20

Answer»

The general form of the equation of a circle is:

(x - h)² + (y - k)² = r²

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, r² = 20

⇒ centre = ( - 5, 3) and radius = √20 = 2√5 units.

Ans: centre = ( - 5, 3) and radius = 2√5 units.

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Find the centre and radius of each of the following circles : (x + 5)2 + (y – 3)2 = 20

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