How do you evaluate # Tan((3pi)/4)#? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer ali ergin Apr 25, 2016 #tan((3pi)/4)=-1# Explanation: #(3pi)/4=pi-pi/4# #a=pi# #b=pi/4# #tan(a-b)=(tan a-tan b)/(1+tan a*tan b)# #tan((3pi)/4)=(tan pi-tan (pi/4))/(1+tan pi*tan (pi/4)# #tan((3pi)/4)=(0-1)/(1+0*1)# #tan((3pi)/4)=-1/1# #tan((3pi)/4)=-1# 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 6721 views around the world You can reuse this answer Creative Commons License