Question

Use a double-angle formula to solve the following for x: sin 2x + sin x = 0

Answer 1

put sin 2x=2sin x cos x
then take sinx common

Answer 2

\(\bf {\color{blue}{ sin(2x)}} + sin(x) = 0\implies {\color{blue}{ 2sin(x)cos(x)}} + sin(x) = 0\)

take common factor
isolate the identity
then take the inverse function of it