Find the Exact Value cos(-630)

Problem

cos(−630^∘)

Solution

1. Use the even-odd property of the cosine function, which states that cos(−θ)=cos(θ)

cos(−630^∘)=cos(630^∘)

2. Find a coterminal angle by adding or subtracting multiples of 360^∘ until the angle is within the range [0^∘,360^∘)

630^∘−360^∘=270^∘

3. Identify the cosine value for the coterminal angle 270^∘ on the unit circle.

cos(270^∘)=0

Final Answer

cos(−630^∘)=0

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