Simplify Trigonometric Expression

[BlueStreak]

Simplify the expression: sin 2θ cosθ + cos 2θ sin θ.

The problem I'm struggling with is above and I can't figure out how to start.

 

[BlueStreak]

If anyone reads this, I accidentally marked this as "solved" even though it's not. I don't know how to unmark it. I'm new here, so I'm trying to learn along the way.

 

[MarkFL]

Hello, and welcome to FMH!

I've marked your thread as unsolved.

To simplify the expression, think of the angle-sum identity for sine...

 

[BlueStreak]

@MarkFL Thank you so much! Would you be referring to this: sinθ = cos (π/2 - θ)

 

[MarkFL]

That's a co-function identity. I'm talking about:

[MATH]\sin(\alpha\pm\beta)=\sin(\alpha)\cos(\beta)\pm\cos(\alpha)\sin(\beta)[/MATH]

 

[BlueStreak]

@MarkFL Oh, okay. Sorry, I was confused. I'll try it. Thank you! I appreciate it!

 

[BlueStreak]

My answer is sin 3θ. Bless you. The help was much appreciated. ?

 

[MarkFL]

My answer is sin 3θ. Bless you. The help was much appreciated. ?

Yes...excellent!