Question

Find the equation of the circle whose centre is (-1,2) radius 4

Answer 1

Then General Equation of circle with centre (a,b) and radius r is
(x-a)² + (y-b)²=r²
Subtituting a=-1,b=2 and r=4
(x+1)² + (y-2)²=16

Answer 2

Answer

Here it is given that centre (h,k)=(−2,3) and radius r=4

Therefore the equation of the circle is

(x+2) ^2 +(y−3) ^2=(4) ^2

⇒x^2 +4x+4+y ^2 −6y+9=16

⇒x ^2 +y ^2 +4x−6y−3=0