What is cos 135? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer Dreamer.N · Stefan V. May 7, 2018 The value of #cos 135# is #-1/sqrt(2)#. Explanation: We have #cos 135#. #135= (3pi)/4# So #cos((3pi)/4)=cos(pi-pi/4)# # =-cos(pi/4)# # =-1/sqrt2# Hope it helps!! 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 31202 views around the world You can reuse this answer Creative Commons License