How do I simplify my trignometric matrices??

I have tried using "simplify" command. MATLAB simplifies it to some extent but not completely. The code is as below:

if true
  %clc
clear all
syms o l1 l2 l0;
A=[ cos(o)      -sin(o)         1;
  cos(o-120)  -sin(o-120)     1;
  cos(o-240)  -sin(o-240)     1;
  ]
X=inv(A)
W=simplify(X)
end

The anwer of the first element of matrix "W" is shown as

if true
  % -(sin(o - 120) - sin(o - 240))/(2*sin(120) - sin(240))
end

clearly which can be further simplified (by applying formulas of Sin(a-b)) to give answer of Cos(o)... What am I doing wrong here??

[Torsten]

First of all, replace 120 by 2/3*pi and 240 by 4/3*pi (sin and cos work with radians, not with degrees).

Best wishes

Torsten.

Answer 1

[Star Strider]

Tell the simplify function to keep working on it:

W=simplify(X, 'steps', 20)

Also, as Torsten mentioned, the Symbolic Toolbox trigonometric functions require their arguments be in radians not degrees, so multiply the constants by ‘pi/180’.