All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Just Math
Trigonometric Fun (Posted on 2004-12-06) Difficulty: 4 of 5
Show that cos(π/7) - cos(2π/7) + cos(3π/7) = 1/2.

See The Solution Submitted by SilverKnight    
Rating: 3.6667 (3 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Arbitrary Evaluation | Comment 2 of 7 |

Perhaps someone will be so kind as to explain this one to me. I am thinking that n can be any number, so I arbitrarily choose 35 and observe hierarchy and do not get that cos5-cos10+cos15 = 1/2.

I'm not familiar with the principle involved but if such a thing does exist then wouldn't it be a modulus behaviour based on the cyclic properties of sine and cosine functions?

Thank you. Hugs. -CeeAnne-

  Posted by CeeAnne on 2004-12-06 21:20:43
Please log in:
Remember me:
Sign up! | Forgot password

Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (2)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Copyright © 2002 - 2018 by Animus Pactum Consulting. All rights reserved. Privacy Information