Find the maximum value and minimum value of each of the following functions. Give the least positive values of x at which they occur.
Hence the function will be minimal when the denominator will be maximal, that is to say when cos(1/2 x -45) will be minimal, ie = -1
-> x/2 -45=pi+2kpi
-> x=2pi+90+4kpi=(4k+2)pi + 90
So you have to find k such as x is positive and the least positive.