Question

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

Answer 1

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.