Simplify #sin(9A)+sin(5A)#?

1 Answer
Evan
Nov 25, 2017

#sin(9A)+sin(5A)=2sin(7A)cos(2A)#

Explanation:

This is the sum identity

#sin(x)+sin(y)=2sin((x+y)/2)cos((x-y)/2)#

To solve the equation, let #x=9A# and #y=5A#,

#sin(9A)+sin(5A)=2sin((9A+5A)/2)cos((9A-5A)/2)#
#color(white)(sin(9A)+sin(5A))=2sin(7A)cos(2A)#

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