Question

Solve: ="cos^2(2x)-sin^2(2x)=0" align="absmiddle" class="latex-formula"> Thanks

Answer 1

Answer:

x = pi/8   + pi/2  *n                    x = 3pi/8   +   pi /2 *n

Step-by-step explanation:

cos ^2 ( 2x) - sin ^2 (2x) = 0

Substitute u = 2x

cos ^2 ( u) - sin ^2 (u) = 0

We know cos ^2(x)-sin ^2(x)=cos (2x)

cos ( 2u) =0

Replacing u with 2x

cos  (2 *2x) =0

cos (4x) =0

cos u =0 when u = pi/2 + 2 pi n and 3pi/2 + 2 pi n  where n is an integer

4x = pi/2+2 pi n                    4x = 3pi/2+2pi n

x = pi/8   + pi/2  *n                    x = 3pi/8   +   pi /2 *n