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prove that: cos x − cos (x − π/3 ) ≡ cos (x + π/ 3 ) watch
- Thread Starter
- 22-01-2015 09:27
- 22-01-2015 09:31
You will probably find answers faster in the Maths Help Forum
- 22-01-2015 10:45
I think you are supposed to use the identities for cos(a +/- b) and simplify it.
I tried it and its not coming for me. lel..Last edited by Ifailedumad; 22-01-2015 at 10:54.
- 22-01-2015 15:16
1. Carefully using the addition formula for cos(A + B) on both sides of your equation you can show LHS=RHS
2. Use the addition formula on the LHS, then use your preferred method to rewrite the result in the form Rcos(x+theta)
Remember pi/3 is a special angle with exact trig values.
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