# trig

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I don't understand why cos is 135

• trig -

for the cosine = -sqrt 2/2 negative x axis
It could be either 180 + 45 or 180 - 45
so either 135 or 225
for the sine = -sqrt 2/2
that is 180 + 45 or 360 - 45
so either 225 or 315

225 satisfies both the sine and the cosine.

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