2 Answers

Joe Slater · Answer 1 · 2018-10-13T08:17:38+0000

The cosine repeats every 2pi, so the terms of the expression are all equal, and you have 5 cos(pi/11), which totals up to about 4.797 .

Piyush Sonigra · Answer 2 · 2018-10-15T18:45:01+0000

Using a calculator, the answer will be 1/2 as a result of all the / and use of opposite πs that form 18 making a whole circle.

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