Find the number of solutions of cos(x)+cos(2x)+cos(3x)+cos(4x)+cos(5x)=5 in the interval [0,2π]

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Solution

As you know maximum value of cos is 1
So to get 5 As answer from the LHS,
All the terms in LHS should be
1
So to get 1 in all LHS term...
X should be 0
Since x in between (0-2pi)
Only solution is 0

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