Find the Exact Value cos(330)

Problem

cos(330)

Solution

1. Identify the reference angle by finding the difference between 330 and 360

(θ_ref)=360−330

(θ_ref)=30

2. Determine the quadrant in which 330 lies. Since 270<330<360 the angle is in Quadrant IV.

3. Determine the sign of the cosine function in Quadrant IV. In this quadrant, the xcoordinates are positive, so cos(330) is positive.

cos(330)=cos(30)

4. Evaluate the exact value of cos(30) using the unit circle or a special right triangle.

cos(30)=√(,3)/2

Final Answer

cos(330)=√(,3)/2

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