angle between three points (in 3D)?

Hello Everyone,

I am trying to find an angle between two segments (Shoulder - Elbow and Elbow - Wrist) where Shoulder, Elbow and Wrist are the three points in the space which have x, y and z points and they have 1000 points. I am a little confused about how to calculate the angle when I have 1000 points? For the reference, I have attached the excel document and the figure. Thank you !

PA

Answer 1

[darova]

Use dot product

Answer 2

[James Tursa]

See the discussion in these links:

https://www.mathworks.com/matlabcentral/answers/101590-how-can-i-determine-the-angle-between-two-vectors-in-matlab

https://www.mathworks.com/matlabcentral/answers/501449-angle-betwen-two-3d-vectors-in-the-range-0-360-degree