Question

In the following find the centre and radius of the circles: $x^{2} +y^{2}-4x-8y-45=0$

Answer 1

here is answer take the following step( s) into consideration !!!

center => (-g , -f ) = (2 , 4 )

radius => √ g²+ f ²-c

radius => √ 4 + 16 +45

=> radius =√ 65

hope it help you !!

thanks !!

Answer 2

Answer:

centre of given circle is ( 2,4)

radius = √65 units

Step-by-step explanation:

The given equation is x²+y²-4x-8y-45=0

We know that the standard equation of the circle is

x²+y²+2gx+2fy+c=0

where (-g,-f) are center of circle

and √(g²+f²-c) is radius

Now compare the equation with  standard equation to get center and radius

here

x²+y²-4x-8y-45=0

2gx = -4x

g = -2

2fy=-8y

f= -4

So,centre of given circle is ( 2,4)

Radius √4+16+45

r = √65 units