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Prove that: Cos2pi/7+cos4pi/7+cos8pi/7=-1/2
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Prove that: Cos2pi/7+cos4pi/7+cos8pi/7=-1/2

User Evan Shortiss
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1 Answer

1 vote

Answer:

1. use a calculator to help

2. that's wrong because it equals 1.333...

User Trond Kristiansen
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