Find the Exact Value cos(-45 degrees )

Problem

cos(−45^∘)

Solution

1. Apply the even-odd identity for the cosine function, which states that cos(−θ)=cos(θ)

cos(−45^∘)=cos(45^∘)

2. Identify the exact value of cos(45^∘) using the unit circle or a special right triangle (45^∘−45^∘−90^∘.

cos(45^∘)=√(,2)/2

Final Answer

cos(−45^∘)=√(,2)/2

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