Lesson Steps:

Sin 210 = sin (270 - 60) = sin (3 x 90 - 60) = - cos 60 = - 1/2 <=ANS

Another Method:

sin 210 = sin (360 - 150)= - sin 150 = - sin (180 - 30) = - sin (2 x 90 - 30)

= - sin 30 [Since, 150 lies in 2nd quadrant & sin is +ve]
= - 1/2

Answer:

1/2

Level: College
Subject: Math
Topic: Trigonometry