Find the Value Using the Unit Circle cos((3pi)/4)

Problem

cos((3*π)/4)

Solution

1. Identify the angle (3*π)/4 on the unit circle, which is located in the second quadrant.

2. Determine the reference angle by subtracting the angle from π

Reference Angle=π−(3*π)/4=π/4

3. Recall the cosine value for the reference angle π/4

cos(π/4)=√(,2)/2

4. Apply the sign for the second quadrant, where xcoordinates (cosine values) are negative.

cos((3*π)/4)=−√(,2)/2

Final Answer

cos((3*π)/4)=−√(,2)/2

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