What is the radius of a circle whose equation is x2+y2+8x-6y+21=0?

Radius=2

Center: (-4,3)

Step-by-step explanation:

The general equation of a circle is

(x-xo) ² + (y-yo) ²=r², where (xo, yo) are the coordinates of the center, and r is the radius.

Now: x²+y²+8x-6y+21=0

x²+8x+y²-6y+21=0

(x²+8x+16-16) + (y²-6y+9-9) + 21=0

(x²+8x+16) - 16 + (y²-6y+9) - 9+21=0

(x+4) ² + (y-3) ²-16-9+21=0

(x+4) ² + (y-3) ²=16+9-21=25-21=4=2²

So

(x+4) ² + (y-3) ²=2².

Thus, the radius is 2.

The center is at (-4,3)

the radius is 2