Consider the integral I = / cos (4x)da. a) Choose the most appropriate trigonometric identity that will allow you to calculate the integral: O sin"(At) cos2 ( At) = _ sin?(2.At) O cos?(At) = 1 - sin?(At) O sin(At) cos( At) = > sin(2.At) O cos2( At) = = [1 + cos(2.At) O sin (At) = 1 - cos2 (At) sin (At) = = [1 - cos(2.At) ] b) Now compute the integral. I = 1/4