## Algebra and Trigonometry 10th Edition

$2 (\sin 5 \theta +\sin \theta)$
By using the Sum and Difference formulas: $\sin (a+b)=\sin a \cos b +\cos a \sin b$ and $\sin (a-b)=\sin a \cos b -\cos a \sin b$ Now, we will write the expression: Therefore,$\dfrac{4}{2}[\sin 3 \theta +2 \theta +\sin 3 \theta-2 \theta]$ or, $=2 (\sin 5 \theta +\sin \theta)$