Answer:
centre = (- 4, 2 ) , radius = 5
Explanation:
the equation of a circle in standard form is
(x - h )² + (y - k )² = r²
where (h, k ) are the coordinates of the centre and r is the radius
x² + 8x + y² - 4y = 5
using the method of completing the square
add ( half the coefficient of the x/ y terms )² to both sides )
x² + 2(4)x + 16 + y² + 2(- 2)y + 4 = 5 + 16 + 4
(x + 4)² + (y - 2)² = 25 ← in standard form
with (h, k ) = (- 4, 2 ) and r =
= 5
centre = (- 4, 2 ) and radius = 5