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

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Question 615390: Simplify this
(cos theta +1)(cos theta -1)
I cannot figer this out help me
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
%28cos%28theta%29%2B1%29%28cos%28theta%29+-1%29
Just use FOIL or the %28a%2Bb%29%28a-b%29+=+a%5E2-b%5E2 pattern to multiply. I like using the patterns myself:
cos%28theta%29%5E2-1%5E2%29
which simplifies to:
cos%28theta%29%5E2-1%29
This may be an acceptable answer.

But we can go a little further. You might notice that since sin%5E2%28theta%29+=+1+-+cos%5E2%28theta%29, the expression we have is the negative of sin%5E2%28theta%29. If you don't notice this then you could use substitute 1-sin%5E2%28theta%29 for cos%5E2%28theta%29:
%281-sin%5E2%28theta%29%29+-+1
The 1's cancel, leaving
-sin%5E2%28theta%29

So
cos%5E2%28theta%29-1%29
might be good enough but
-sin%5E2%28theta%29
is even simpler.