How do I find the value of cos pi/12? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer Konstantinos Michailidis Sep 11, 2015 It is cos(pi/12)=1/4*(sqrt2+sqrt6) Explanation: It is cos(pi/12)=cos(pi/3-pi/4)=cos(pi/4)cos(pi/3)+sin(pi/4)sin(pi/3)=sqrt2/2*1/2+sqrt2/2*sqrt3/2=1/4*(sqrt2+sqrt2*sqrt3)=1/4(sqrt2+sqrt6) 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 4111 views around the world You can reuse this answer Creative Commons License