Work within your parenthesis first, as you always should. Cos theta + cos theta is 2 cos theta. Square that and you have 4 cos^2 theta. Since both sets of parenthesis are exactly the same, you have [tex]4cos ^{2} \beta +4cos ^{2} \beta [/tex] which are like terms. Add them and you have 8 of them. So your choice is C.
