the correct answer is -1/9
Step-by-step explanation
cos(2A)
=cos(A+A)
=cosA.cosA - sinA.sinA
=cos ^2A- sin^2A
=cos^2A - 1 + cos^2A
=2cos^2A-1
putting the value of cos A -2/3
2*(-2/3)^2-1
=2*4/9-1
=8/9-1
=-1/9
here is put theta as A because I don't find theta symbol
don't forget to mark as brainllest answer