+128707 We can show, using trigonometry, that any point (x, y) on a circle of radius R can be expressed as
(Rcosθ, Rsinθ) where θ is just some angle
So
x^2 + y^2 = R^2cos^2θ + R^2sin^2θ = R^2(cos^2θ + sin^2θ)
But..... (cos^2θ + sin^2θ) = 1 ......so we have
x ^2 + y^2 = R^2
And if we let R = √41, then R^2 = 41 and we have
x^2 + y^2 = 41
And there you go......!!!
+128707 We can show, using trigonometry, that any point (x, y) on a circle of radius R can be expressed as
(Rcosθ, Rsinθ) where θ is just some angle
So
x^2 + y^2 = R^2cos^2θ + R^2sin^2θ = R^2(cos^2θ + sin^2θ)
But..... (cos^2θ + sin^2θ) = 1 ......so we have
x ^2 + y^2 = R^2
And if we let R = √41, then R^2 = 41 and we have
x^2 + y^2 = 41
And there you go......!!!
+118613 On a more basic level
the formula of any circle in the x,y plane is
$${\left({\mathtt{x}}{\mathtt{\,-\,}}{\mathtt{h}}\right)}^{{\mathtt{2}}}{\mathtt{\,\small\textbf+\,}}{\left({\mathtt{y}}{\mathtt{\,-\,}}{\mathtt{k}}\right)}^{{\mathtt{2}}} = {{\mathtt{r}}}^{{\mathtt{2}}}$$
where (h,k) is t he centre and r is the radius :)
