Ill give a medal and fan anyone who can show me how to do this and give me the correct answer.!!

Verify: cos(180° + x) = -cos x.

Please! I tried to type this in google to learn how to do it and it litterly said no results. so i dont even know where to start:/

Question

Ill give a medal and fan anyone who can show me how to do this and give me the correct answer.!!

Verify: cos(180° + x) = -cos x. 

Please! I tried to type this in google to learn how to do it and it litterly said no results. so i dont even know where to start:/

ddcamp · Answer

Maybe a glance at the unit circle could help:
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