How do you evaluate cos(-pi/6) cos (pi/4)cos(−π6)cos(π4)? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer Nghi N. Jun 17, 2016 sqrt6/4√64 Explanation: Trig table --> cos (pi/4) = sqrt2/2cos(π4)=√22 cos (-pi/6) = cos (pi/6) = sqrt3/2cos(−π6)=cos(π6)=√32 P = cos (pi/4).cos (-pi/6) = (sqrt2/2)(sqrt3/2) = sqrt6/4P=cos(π4).cos(−π6)=(√22)(√32)=√64 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^\circ140∘? How do you find the value of cot 300^@cot300∘? What is the value of sin -45^@sin−45∘? How do you find the trigonometric functions of values that are greater than 360^@360∘? How do you use the reference angles to find sin210cos330-tan 135sin210cos330−tan135? How do you know if sin 30 = sin 150sin30=sin150? How do you show that (costheta)(sectheta) = 1(cosθ)(secθ)=1 if theta=pi/4θ=π4? See all questions in Trigonometric Functions of Any Angle Impact of this question 3130 views around the world You can reuse this answer Creative Commons License