How to solve this question?

[raymond]

 

[topsquark]

A starting point:
[math]sin(2 \theta ) = 2~sin( \theta )~cos( \theta )[/math]
How do you find [math]sin( \theta )[/math] and [math]cos( \theta )[/math]?

-Dan

 

[Steven G]

It happens to me all the times when I send an email without the attachment I meant to include.
You forgot to upload the work you have done on this problem.
When you get a chance can you please do so

 

[bZNyQ7C2]

Isn't there an identity about \(\displaystyle \sin \left( {\theta + {\textstyle{\pi \over 2}}} \right)\)?
Or maybe \(\displaystyle \sin \left( {\theta - {\textstyle{\pi \over 2}}} \right)\)?

 

[Romsek]

\(\displaystyle \sin\left(\theta \pm \dfrac \pi 2\right) = \pm \cos(\theta)\)

 

[bZNyQ7C2]

Thanks. I was looking at the diagram, and thinking that might help.

 

[Dr.Peterson]

I would just directly use the definition of the trig functions based on a point on the terminal ray. There is no need to use such an identity here to find [MATH]sin\theta[/MATH] and [MATH]cos\theta[/MATH]. The important part of the problem, of course, is the identity for [MATH]\sin(2\theta)[/MATH].