1
$\begingroup$

How do I simplify the expression of $\cos(2x+3x)\cos x+\sin(3x)\cos\left(\frac x2+x\right)$ ?

  • 0
    I've fixed tex, please check that I didn't modify anything.2012-05-26
  • 3
    Why did you write it as $2x+3x$ instead of $5x$?2012-05-26
  • 2
    @JoeL. is it possible to use (cos(2x)+cos(3x))⋅cosx ?? i calculated and found (for example,in degrees) cos(15)+cos(30) != cos(45) :(2012-05-26
  • 0
    A simple simplification is $\,\cos (2x+3x)=\cos 5x\,$...is there a typo here?2012-05-26
  • 0
    hat do you want to simplify it into? It can be done cleanly into a function of $\cos(x/2)$ and $\sin(x/2)$.2012-05-26
  • 0
    @JoeL. : _How_ did you conclude that $\cos(2x+3x)\cos x$ is the same as $(\cos(2x)+\cos(3x))\cos x$ The two functions don't have the same period.2012-05-26

1 Answers 1