Show that the equation $\cos(x) = \ln(x)$ has at least one solution on real number I have question 

Q
  Show that the equation $\cos (x) = \ln (x)$ has at least one solution on real number.

to solve this question by using intermediate value theorem
we let $f(x)=\cos (x)-\ln (x)$
we want to find $a$ and $b$
but what i should try 
to get $f(a)f(b)<0$
I means 
$f(a)>0$
$f(b)<0$
thanks

Plot the graph and you will see immediately.
