prove that: cos x − cos (x − π/3 ) ≡ cos (x + π/ 3 )

missdentist10

Reply 1

loperdoper

You will probably find answers faster in the Maths Help Forum

Reply 2

gdunne42

Original post by missdentist10

Don't know what constitutes "proof" at the level of maths you are studying
1. Carefully using the addition formula for cos(A + B) on both sides of your equation you can show LHS=RHS
Or
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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