Question 436794
Set it equal to zero and use Newton's method. A simpler way might be to rearrange some variables first:


{{{dA/dx = 8 cos(x/2) - 4x*sin(x/2) = 0}}}


{{{8cos(x/2) = 4x*sin(x/2)}}} Divide through by cos(x/2)


{{{8 = 4x*tan(x/2)}}}


{{{2/x = tan(x/2)}}}


{{{tan(x/2) - 2x = 0}}}


Now just solve using Newton's method and your calculator. You will have to define a recursive sequence using an initial guess, as well as the function and the derivative of that function. Make sure your angles are set to radians.