How do you find the value of $sin (-120)$ ?

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Answer 1 · 2015-10-20T18:34:11

$sin(-120^@) = -sqrt(3)/2$

$120^@$ is equivalent to a reference angle of $60^@$ in Quadrant III

$sin(60^@) = sqrt(3)/2$
but in Quandrant III the $sin$ is negative (using CAST notation)

so $sin(-120^@) = -sqrt(3)/2$

How do you find the value of sin (-120) sin (-120) ?