Can anybody

Find the sum of

cos 1 deg. + cos 3 deg. + cos 5 deg.+ ... + cos 177 deg. + cos 179 deg.

- Dec 4th 2010, 05:07 AMrcscos 1 deg. + cos 3 deg. + cos 5 deg.+ ... + cos 177 deg. + cos 179 deg.
Can anybody

Find the sum of

cos 1 deg. + cos 3 deg. + cos 5 deg.+ ... + cos 177 deg. + cos 179 deg. - Dec 4th 2010, 06:59 AMSoroban
Hello, rcs!

Quote:

Recall the sum-to-product identity:

. .

Then take the pairs of cosines "from each end":

. .

- Dec 4th 2010, 03:19 PMTheCoffeeMachine

Putting , and ranging from to :

- Dec 4th 2010, 04:28 PMArchie Meade