Question

Hey mate,
Here's your question.
Express each of the following as product of 2 trigonometric ratios.​

Answer 1

$\: \: \: \: \: sin4x + sin3x \\ = 2sin( \frac{4x + 3x}{2} )cos( \frac{4x - 3x}{2} ) \\ = 2sin( \frac{7x}{2} )cos( \frac{x}{2} )$

$... \: since \: sinx + siny = 2sin( \frac{x + y}{2} )cos( \frac{x - y}{2} )$