Trigonometry sin and cos question

  • Thread starter _Andreas
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144
1
My teacher told me that

C sin(k x) + D cos(k x) = F sin(k x+gamma)

if neither C nor D is 0 (gamma is a phase angle). How do you derive the expression on the right of the equal sign from that on the left?
 
Last edited:
2,036
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While normally one would say C and D assume certain values, I'll let you find what those values are. Expand the expression on the right and equate the terms on both sides.
 
144
1
While normally one would say C and D assume certain values, I'll let you find what those values are. Expand the expression on the right and equate the terms on both sides.
Actually, I just found out that my course book provides the answer to my question. :blushing: Sorry for bothering! But thanks anyway.

So, note to self: always look in your books before posting questions here.
 
979
1
The relevant trig identity is [tex]\sin (A+B) = \sin A \cos B + \sin B \cos A[/tex].
 

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