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How does Cos 5pi/6turn into -square root of 3 divided by 2Please explain why I am very confused. thank you

User Maccurt
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1 Answer

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Cos 5π/6

Looking at the trigonometric unit circle:

Cos (-π/6+π) = -cos π/6

Looking at the trigonometric table of Special arcs:

-cos π/6= -√3/2

User Keshet
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