Question #01ea9 Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer Andrea S. Dec 4, 2016 #tan (pi/8) = 1/(1+sqrt(2))# Explanation: We have that: #tan (pi/8) = tan(1/2*pi/4)# Using the half angle formulae: #tan (alpha/2) = frac sin alpha (1+cos alpha)# #tan (pi/8) = frac sin(pi/4) (1+cos(pi/4)) = frac (sqrt(2)/2) (1+sqrt(2)/2) = 1/(1+sqrt(2))# 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 1360 views around the world You can reuse this answer Creative Commons License