How do you evaluate sine, cosine, tangent of #-405^circ# without using a calculator? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer sankarankalyanam Feb 20, 2018 #sin(-405) = -(1/sqrt2)# #cos(-405) = (1/sqrt2)# #tan(-405) = -1# Explanation: #sin (-405) = sin (-360 - 45) = sin (-45) = - sin 45= -(1/sqrt2)# #cos (-405) = cos (-360 - 45) = cos (-45) = cos 45= (1/sqrt2)# #tan (-405) = tan (-360 - 45) = tan (-45) = - tan 45= -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 4777 views around the world You can reuse this answer Creative Commons License