Find-all-continuous-real-function-f-such-that-f-ln-x-y-f-sin-xy-f-cos-y-x-for-all-x-y-R-

Question Number 110460 by ZiYangLee last updated on 29/Aug/20

Find all continuous real function f

such that

f (\ln (x + y)) = f (\sin (x y)) + f (\cos (y / x))

for all x, y \in R^{+} .