What is the exact value of sec 210? Trigonometry Right Triangles Trigonometric Functions of Any Angle 1 Answer Nghi N. May 7, 2015 sec 210 = 1/cos 210 = 1/cos (30 + 180) = 1/(-cos 30) . Since (-cos 30) = (-sqr3)/2, then sec 210 = -2/(sqr3) = -(2.sqr3)/3 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 26300 views around the world You can reuse this answer Creative Commons License