Evaluate cos(-1)

Problem

cos(−1)

Solution

1. Identify the parity of the cosine function. The cosine function is an even function, which means it satisfies the identity cos(−θ)=cos(θ)

2. Apply the identity to the given expression where θ=1

cos(−1)=cos(1)

3. Determine the value. Since 1 is not a standard angle (like π/4 or π/3, the expression is typically left in its exact form cos(1) or approximated using a calculator.

4. Approximate the value in radians if a decimal is required.

cos(1)≈0.5403023

Final Answer

cos(−1)=cos(1)

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