[tex]\begin{gathered} \cos ^2x-sin^2x\text{ = }\cos 2x \\ So,\text{ }\sin ^2x-\text{ }\cos ^2x\text{ = -}\cos 2x \end{gathered}[/tex][tex]\begin{gathered} \text{Thus, -}\cos 2x\text{= 0} \\ In\text{ general }\cos (y)\text{ = 0 implies y = }\frac{n\pi}{2} \end{gathered}[/tex][tex]\begin{gathered} -\cos (2x)\text{ =0} \\ 2x\text{ = }\frac{n\pi}{2} \\ x\text{ =}\frac{n\pi}{4} \\ \end{gathered}[/tex]
The interval [0, 6.28] = [0, 2 x 3.14] = [0 , 2pi]
[tex]\begin{gathered} So\text{ if the interval is (0, 2}\pi) \\ \text{the values are } \\ \frac{\pi}{4},\text{ }\frac{3\pi}{4},\text{ }\frac{5\pi}{4}\text{ , }\frac{7\pi}{4} \end{gathered}[/tex]
