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Question: Question about applyrule

Question:Question about applyrule

jeilerts 50 Maple
applyrule
February 04 2013
0

Hi,

I have an expression which contains terms like cos(3*x)*cos(x) + sin(3*x)*sin(x). In this expression, I replace the prevous terms by using applyrule as:

applyrule([cos(3*x)*cos(x)=1/2*(cos(2*x)+cos(4*x)), sin(3*x)*sin(x)=1/2(cos(2*x)-cos(4*x))],expr);

 

Is there a way to generalize this so that I may replace all forms of sin(n*x)*sin(m*x) = 1/2(cos((n-m)*x)-cos((n+m)*x))?

 

Thanks for your help.
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