Evaluate cos(135 degrees )

Problem

cos(135)

Solution

1. Identify the angle in the unit circle. The angle 135 is located in the second quadrant.

2. Determine the reference angle. Since 135 is in the second quadrant, the reference angle is calculated as 180−135=45

3. Recall the cosine value for the reference angle. The value of cos(45) is √(,2)/2

4. Apply the sign for the second quadrant. In the second quadrant, the cosine function is negative.

5. Combine the sign and the value to find the result.

Final Answer

cos(135)=−√(,2)/2

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