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Why is sin(20) = sin(160) = -sin(200) = -sin(340)?
5 months ago
Q:
Why is sin(20) = sin(160) = -sin(200) = -sin(340)?
Accepted Solution
A:
The sine is positive in second quadrant so sin 20 = sin (180-20) = sin 160.
The sine is negative in the third quadrant so sin (180+20) = -sin 20
so sin 20 = - sin 200
The sine is negative in fourth quadrant so sin 340 = -sin 20 and sin 20 = - sin 340.