Find the Value Using the Unit Circle cos((7pi)/4)

Problem

cos((7*π)/4)

Solution

1. Identify the angle (7*π)/4 on the unit circle.

2. Determine the quadrant by comparing the angle to the axes. Since (3*π)/2<(7*π)/4<2*π the angle is in Quadrant IV.

3. Calculate the reference angle θ′ using the formula θ′=2*π−θ

θ′=2*π−(7*π)/4

θ′=π/4

4. Evaluate the cosine of the reference angle.

cos(π/4)=√(,2)/2

5. Determine the sign of the cosine function in Quadrant IV. In Quadrant IV, the xcoordinate (cosine) is positive.

cos((7*π)/4)=√(,2)/2

Final Answer

cos((7*π)/4)=√(,2)/2

Want more problems? Check here!