sin(2arctan(4))=?
I used to just make a triangle and evaluate it from there but not sure how to go about that with the "2". How should I solve this?

Question

sin(2arctan(4))=?
I used to just make a triangle and evaluate it from there but not sure how to go about that with the "2". How should I solve this?

anonymous · Answer

WELCOME TO OPENSTUDY 
where u can ask questions and answer questions 
and give medals and fan people that helped you so much that want to ask a question you just have to do this @_Stephen_324  to get them to your question!!!!

anonymous · Answer

...

jim_thompson5910 · Answer

Let $\Large \theta = \arctan(4)$


Use an identity to get

$$\Large \sin(2\arctan(4)) = \sin(2\theta)$$

$$\Large \sin(2\arctan(4)) = 2\sin(\theta)\cos(\theta)$$

$$\Large \sin(2\arctan(4)) = 2\sin(\arctan(4))\cos(\arctan(4))$$

jim_thompson5910 · Answer

Hopefully you see what to do from here

anonymous · Answer

Thank You!

jim_thompson5910 · Answer

you're welcome