Question

Find the equation of the circle with centre (1, 1) and radius `sqrt2`.

Answer 1

The equation of a circle with centre (h, k) and radius r is given as

(x­ – h)² + (y ­– k)² = r²

It is given that centre (h, k) = (1, 1) and radius (r) =`sqrt2`

Therefore, the equation of the circle is

= (x + 1)² + (y - 1)² = `(sqrt2)^2`

= x² - 2x + 1 + y² - 2y + 1 = 2

= x² + y² - 2x - 2y = 0