Question
The largest interval lying in $\left( { - {\pi \over 2},{\pi \over 2}} \right)$ for which the function
$f\left( x \right) = {4^{ - {x^2}}} + {\cos ^{ - 1}}\left( {{x \over 2} - 1} \right)$$ + \log \left( {\cos x} \right)$,
is defined, is
$f\left( x \right) = {4^{ - {x^2}}} + {\cos ^{ - 1}}\left( {{x \over 2} - 1} \right)$$ + \log \left( {\cos x} \right)$,
is defined, is