Solving trigonometric equations using sum and difference identities

Lessons

• 1.
  Utilizing "Sum and Difference Identities" to solve:

  
  
  a)

  $\sin (x + {\pi \over 4} ) + \sin (x - {\pi \over 4} ) = -1,$

  general solution in degrees
  
  
  
  b)

  $\cos 3x \cos x + \sin 3x \sin x =0,$

  $0 \leq x$ < $2\pi$
  
  
  

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