Find the Exact Value cos(-270)

Problem

cos(−270^∘)

Solution

1. Identify the angle and its direction. The angle is −270^∘ which indicates a clockwise rotation from the positive x-axis.

2. Find the coterminal angle in the standard range [0^∘,360^∘) by adding 360^∘ to the given angle.

−270^∘+360^∘=90^∘

3. Determine the coordinates on the unit circle for 90^∘ At 90^∘ the point is (0,1)

4. Apply the definition of the cosine function on the unit circle, where cos(θ)=x

cos(90^∘)=0

Final Answer

cos(−270^∘)=0

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