use reference angles to find the exact value of the expression. do not use a calculator. sin-2pi/3?

Question

1. -1/2
2. ^/[]3 over2
3. - ^/[]3 over2
4. -1

Answer 1

3. - √3 / 2
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Ideas: sin(-2pi/3) = -sin(pi - 2pi/3) = -sin(pi/3) = - √3 / 2

Answer 2

2 pi /3 = 120 deg
-120 deg is in the third quad where sin is neg.

sin(60) = root(3) /2

so the answer should be 3.

Answer 3

sin(-2pi/3)
= - sin(2pi/3)
= - sin (2 * 180 /3)
= - sin (120) = -sin(60)
= -sqrt(3)/2
answer is 3