SOLUTION: Simplify this (cos theta +1)(cos theta -1) I cannot figer this out help me

Question 615390: Simplify this
(cos theta +1)(cos theta -1)
I cannot figer this out help me
Answer by jsmallt9(3758) (Show Source): You can put this solution on YOUR website!

Just use FOIL or the pattern to multiply. I like using the patterns myself:

which simplifies to:

This may be an acceptable answer.

But we can go a little further. You might notice that since , the expression we have is the negative of . If you don't notice this then you could use substitute for :

The 1's cancel, leaving

might be good enough but

is even simpler.
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