Question

If the lines x + y + 1 = 0, x – y + 1 = 0 are two diameters of a circle passing through (1,1) then equation of the circle is

Answer 1

x+y+1=0. equ 1

x-y+1=0. equ 2

by sloving these two equ,we get

x+y+1=0

x-y+1=0

2x+2=0

x=-1

by changing the sign,

x+y+1=0

-x+y-1=0

2y=0

y=0

there fore (x,y)=(-1,0)

these points passes through tha point (1,1)

by two points slope form

x-x1/x2-x1 =y-y1/y2-y1

x+1/1+1 =y-0/1-0

x+1/2 =y/1

x+1=2y

x-2y+1=0