Question

If π<2x<3π/2 , then
√{2+√(2+2cos4x)}

Answer 1

lastly it is equals to
+- 2cos theta
now since pi <2theta< 3pi/2..or pi/2 <theta <3pi/4..or 90 <theta <135....so between this range of theta ,cos theta will be negative so the above solution will be equal to -2cos theta