How do you find the sine, cosine, and tangent of (-4pi)/3 radians? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer marfre Jul 4, 2018 #sin ((-4 pi)/3) = 1/2# #cos ((-4 pi)/3) = sqrt(3)/2# #tan((-4 pi)/3) = sqrt(3)/3# Explanation: Given: #(-4 pi)/3# Add #2 pi# to find the positive equivalent angle: #(-4 pi)/3 + (6 pi)/3 = (2 pi)/3# #(2 pi)/3# is in the 2nd quadrant. The reference angle is #pi/3 = 60^@# #sin ((2 pi)/3) = 1/2# #cos ((2 pi)/3) = sqrt(3)/2# #tan ((2 pi)/3) = 1/sqrt(3) * sqrt(3)/sqrt(3) = sqrt(3)/3# 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 9069 views around the world You can reuse this answer Creative Commons License