Question #82719
1 Answer
May 23, 2016
We will use the following identities:
#sin(alpha + beta) = sin(alpha)cos(beta)+cos(alpha)sin(beta)# #sin(2x) = 2sin(x)cos(x)# #cos(2x) = 2cos^2(x)-1#
With those, we have
#=sin(x)cos(2x)+cos(x)sin(2x)#
#=sin(x)(2cos^2(x)-1)+cos(x)(2sin(x)cos(x))#
#=2cos^2(x)sin(x)-sin(x)+2cos^2(x)sin(x)#
#=4cos^2(x)sin(x)-sin(x)#
