# Math Help - Simplify the trig expression

1. ## Simplify the trig expression

tan(arcsin x)

sin(arctan x)

Please Help, I have no idea what to do.

2. Originally Posted by dm10
tan(arcsin x)

sin(arctan x)

Please Help, I have no idea what to do.
Let $\arcsin x = \theta \Rightarrow x = \sin \theta$.

$\tan \theta = \frac{\sin \theta}{\cos \theta} = \frac{x}{\sqrt{1 - x^2}}$.

Therefore $\tan (\arcsin x) = \frac{x}{\sqrt{1 - x^2}}$.

Only the positive root is required (why?).

Try the second one now.

3. Originally Posted by dm10
tan(arcsin x)

sin(arctan x)

Please Help, I have no idea what to do.
Never mind, Mr Fantastic beat me :P