(1) Find the inverse of the linear function
f(x) = mx + b, m does not = 0.
(2) Find the inverse of the function
f(x) = sqrt{r^2 - x^2}, 0 < or = to x < or = to r
$\displaystyle f(x)=mx+b$
$\displaystyle y=mx+b$
Interchange the x and y. Then, solve for y.
$\displaystyle x=my+b$
$\displaystyle my=x-b$
$\displaystyle y=\frac{x-b}{m}$
Actually, Earboth did a good job of explaining this one here: http://www.mathhelpforum.com/math-he...functions.html
And yes, you take the square root of both sides. The inverse is the same as the original function.