For example, if i rotate the function $f(x) = \sqrt{1-x^2}$ over the $x$ axis, i would get the shape $x^2 +y^2 +z^2 = 1$.
And if i rotate the function $g(x) = \sqrt{x} $ over the $x$ axis, i would get the shape $z^2 +y^2 = x$
Is there a general method for finding the equation of shape in $\mathbb{R^3}$ of the rotation of a function $f(x)$ in $\mathbb{R^2}$ over the $x$ or $y$ axis?
Note that, for any $x$, the curve in the $zy$-plane is a circle of radius $|f(x)|$. Thus, the surface equation resulting from the rotation around the $x$-axis is
$$z^2+y^2=[f(x)]^2$$
Similarly, the surface equation resulting from the rotation around the $y$-axis is
$$z^2+x^2=[f^{-1}(y)]^2$$