Question

18. Find the equation of the circle containing the points (-1.-1) and (3, 1) and with the centre on the line x-y + 10 = 0​

Answer 1

x^{2} +2x+y^{2}+2y= 18

Explanation:

equation of circle is:

`x^(2)+y^(2)=r^(2)`

using distance formula and substituting value,

`(3-(-1))^(2) +(1-(-1))^(2)=r^(2)`

solving,

r=
`2√(5)`

for equation of circle,

`(x-(-1))^(2) +(y-(-1))^(2) =20`

on solving,

`x^(2) +2x+1+y^(2)+2y+1=20`

on solving,

`x^(2) +2x+y^(2)+2y= 18`