How can the sum of three cosines equal 1?

  • Thread starter Thread starter Gunthi
  • Start date Start date
  • Tags Tags
    Sum
AI Thread Summary
The discussion centers on proving how the sum of three cosines can equal 1, referencing a specific document for context. The original poster seeks assistance in understanding this mathematical concept. A participant suggests using the Pythagorean theorem to express the length of a point in relation to its coordinates defined by the cosines. This approach leads to the desired relation, confirming the original poster's understanding. The interaction concludes with the original poster expressing gratitude for the help received.
Gunthi
Messages
65
Reaction score
1
Mathematics news on Phys.org
If OP=d, the coordinates of P are (cos α1,cos α2,cos α3)d. Now, express the length of OP using Pythagoras and you get the desired relation.
 
Norwegian said:
If OP=d, the coordinates of P are (cos α1,cos α2,cos α3)d. Now, express the length of OP using Pythagoras and you get the desired relation.

Got it! Thanks!
 

Thread 'Non-orthogonal bases'

Suppose ,instead of the usual x,y coordinate system with an I basis vector along the x -axis and a corresponding j basis vector along the y-axis we instead have a different pair of basis vectors ,call them e and f along their respective axes. I have seen that this is an important subject in maths My question is what physical applications does such a model apply to? I am asking here because I have devoted quite a lot of time in the past to understanding convectors and the dual...
View full post »

Thread 'What Exactly is Dirac’s Delta Function? - Insight'

Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...
View full post »

Similar threads

I Confused about identity for product of cosines into a sum of cosines
Replies
1
Views
1K
A How to use the Newton-Raphson method while keeping the sum constant?
Replies
2
Views
2K
MHB How Do You Solve a Geometric Sum with Alternating Signs?
Replies
2
Views
1K
I Find an explicit formula for this n-sum problem
Replies
7
Views
3K
MHB Can an Ellipse Help Solve the Scalene Triangle Problem?
Replies
1
Views
1K
I Demo of cosine direction with curvilinear coordinates
Replies
16
Views
2K
Finite sum formula for tangent (trigonometry)
Replies
4
Views
3K
MHB How can the sum of digits of a multiple of 2016 equal 2016?
Replies
6
Views
2K
Identifying variables from Riemann sum limits
Replies
3
Views
1K
I How was this substitution possible?
Replies
5
Views
908

Hot Threads

Recent Insights

Back
Top