Question

How do you find the equation of the circle given center (10, -7); and radius 8?

Answer 1

`x^2+y^2-20x+14y-85=0`.

Explanation:

The eqn. of a circle with centre `(h,k)` and radius `r` is given by,

(x-h)^2+(y-k)^2=r^2#.

In our case, the reqd. eqn. is `(x-10)^2+(y+7)^2=8^2.`, i.e.,

`x^2+y^2-20x+14y-85=0`.