Question

What is the radius of a circle with the equation x^2+y^2+2x+4y-9=0

Answer 1

comparing the eq. x^2+y^2+2x+4y-9 with standard eq. of circle

i.e., x^2+y^2+2gx+2fy+c=0

then, 2g = 2,g = 1

and, 2f = 4,f = 2

and, c = -3

hence, centre = (-g,-f) = (-1,-2)

and, radius(square) = g^2+f^2-c

hence, radius = 2

Answer 2

Answer:

3.741

Explanation:

14sqrt= 3.74165738677