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Compute cos(0) + cos(5) + cos(10) + cos(15) + ... + cos(355).  (All angles are in degrees.)

 Jul 4, 2020
 #1
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cos(0)  cancels out  cos(180)

cos(5)  cancels out  cos(175)

...

cos(85)  cancels out cos(5)

 

This leaves you with cos(90); how much is cos(90)?

 

cos(355)  cancels out  cos(185)

cos(350)  cancels out  cos(190)

...

cos(275)  cancels out  cos(265)

 

This leaves you with cos(270); how much is cos(270)?

 

So, how much is  cos(90) + cos(270)?

 Jul 4, 2020

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