another trig question (1 Viewer)

812 · Jan 21, 2012

Prove:

sin(5x) + sin(3x) - 2sin(2x)cos(x) = 2sin(2x)cos(3x)

nightweaver066 · Jan 21, 2012

812 said:
Prove:

sin(5x) + sin(3x) - 2sin(2x)cos(x) = 2sin(2x)cos(3x)

LHS: sin(5x) + sin(3x) - 2sin(2x)cos(x)
= 2sin(4x)cos(x) - 2sin(2x)cos(x)
= 2cos(x)[sin(4x) - sin(2x)]
=2cos(x)[2cos(3x)sin(x)]
= 2sin(2x)cos(3x) = RHS

another trig question (1 Viewer)

812

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nightweaver066

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