Question

What is the equation of the tangent line of `f(x) =sqrt(ln(sinx))` at `x = pi/4`?

Answer 1

There is none.

Explanation:

Since `ln(sin(pi/4))=ln(1/sqrt{2})=-1/2 ln 2` is a negative number, `f(pi/4)` is not defined. Hence, there is no tangent line there.