Question

cos200 + cos 40° + cos 60° + ..... + cos160° + cos180º =
1)
2) 1
3) -1​

Answer 1

Answer:

(3)-1

Step-by-step explanation:

Note that cos (180 - x) = -cos(x)

So, terms like Cos(20) and Cos(160) will get cancelled

Only term left will be Cos(180) which is -1

So, the answer is -1

Hope it helps