Assuming the right expression is
[cos(theta) + cos(theta) ]^2 + [cos(theta) + cos(theta)]^2, the solution is:
[2cos(theta)]^2 + [2cos(theta)]^2 = 4 [cos(theta)]^2 + 4 [cos(theta)]^2 =startin
= 8 [cos(theta)]^2.
If the starting expression is different, please type it and the list of choices again, making sure that the operators can be understood unambiguosly.