How do you evaluate cos 8(pi)? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer Somebody N. Mar 30, 2018 1 Explanation: Notice that one complete rotation is 2pi: So 8pi is just 4 complete rotations. We therefore only need to find: cos(0) cos(0)=1 Answer link Related questions How do you find the trigonometric functions of any angle? What is the reference angle? How do you use the ordered pairs on a unit circle to evaluate a trigonometric function of any angle? What is the reference angle for 140^\circ? How do you find the value of cot 300^@? What is the value of sin -45^@? How do you find the trigonometric functions of values that are greater than 360^@? How do you use the reference angles to find sin210cos330-tan 135? How do you know if sin 30 = sin 150? How do you show that (costheta)(sectheta) = 1 if theta=pi/4? See all questions in Trigonometric Functions of Any Angle Impact of this question 4843 views around the world You can reuse this answer Creative Commons License