Question
माना $f(x) = \left| {\begin{array}{*{20}{c}}{\,\sec x}&{\cos x}&{{{\sec }^2}x + \cot x\,{\rm{cosec}}\,x\,}\\{{{\cos }^2}x}&{{{\cos }^2}x}&{{\rm{cose}}{{\rm{c}}^2}x}\\1&{{{\cos }^2}x}&{{{\cos }^2}x}\end{array}} \right|\,,$ तब $\int_0^{\pi /2} {\,f(x)\,dx = } $