Question

How do you write the equation for a circle with with Radius 10 and centre (2, 1)?

Answer 1

`x^2+y^2-4x-2y-95=0`

Explanation:

As the center is `(2,1)` and radius `10`, circle is locus of a point that is at a distance `10` from `(2,1)`.

Hence, `(x-2)^2+(y-1)^2=10^2` or

`x^2-4x+4+y^2-2y+1=100` or

`x^2+y^2-4x-2y+5-100=0` or

`x^2+y^2-4x-2y-95=0`