Rewrite as a sum?

Question

Rewrite as a sum: #6(sin 5theta) cos 2 theta#

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Answer 1 · 2018-03-14T09:45:23

#rarr6sin5x*cos2x=3sin7x+3sin3x#

Use #rarr2sinA*cosB=sin(A+B)+sin(A-B)#

#rarr6sin5x*cos2x#

#=3*[2sin5x*cos2x]#

#=3*[sin(5x+2x)+sin(5x-2x)]#

#=3*[sin7x+sin3x]=3sin7x+3sin3x#