Prove each trig identity below.

(1) cos(pi/2 + x) = -sin(x)

(2) cos(A + B) + cos(A - B) = 2 cosA cos B

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- Aug 26th 2008, 05:42 AMmagentaritaProving Trig Identities
Prove each trig identity below.

(1) cos(pi/2 + x) = -sin(x)

(2) cos(A + B) + cos(A - B) = 2 cosA cos B - Aug 26th 2008, 06:03 AMMoo
- Aug 26th 2008, 06:03 AMChop Suey

For both questions, prove the LHS. I want to see your attempt and people will point out any mistakes, if any. - Aug 26th 2008, 08:53 PMmagentaritaTips...