Respuesta :
Answer:
The radius of the circle 'r' = 5
Equation of the circle
(x - 2 )² + (y+1)² = (5)²
center of the circle ( h,k) = (2 , -1) , 'r' = 5
Step-by-step explanation:
Step(i):-
Given circle is x² - 4 x + y² + 2 y - 20 =0
x² - 2(2) x + (2)²-(2)²+ y² + 2 y(1) +(1)²-(1)² - 20 = 0
We know that
(a+b)² = a²+2 a b+b²
(a-b)² = a² -2 a b+b²
⇒(x - 2 )² - 4 + (y+1)² -21 =0
⇒ (x - 2 )² + (y+1)² = 25
Step(ii):-
Equation of the circle form
( x- h)² + (y -k)² = r²
Given circle (x - 2 )² + (y+1)² = (5)²
center of the circle ( h,k) = (2 , -1)
radius of the circle 'r' = 5
