Find the Exact Value cos(-300 degrees )

Problem

cos(−300)

Solution

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

cos(−300)=cos(300)

2. Find the coterminal angle or use the unit circle to identify the position of 300 Since 300 is in the fourth quadrant, the cosine value will be positive.

300=360−60

3. Determine the reference angle by subtracting the angle from 360

Reference Angle=360−300=60

4. Evaluate the cosine of the reference angle using the special right triangle values.

cos(60)=1/2

5. Combine the results noting that cosine is positive in the fourth quadrant.

cos(300)=1/2

Final Answer

cos(−300)=1/2

Want more problems? Check here!