1. ## Differentiation help

Prove that $\frac{d}{dx} \arcsin x=\frac{1}{\sqrt{1-x^2}}$
Given that the variables x and y satisfy the equation
$\arcsin 2x+\arcsin y+\arcsin (xy)=0$
find $\frac{dy}{dx}$ when x=y=0

I have done the first part, proving $\frac{d}{dx} \arcsin x=\frac{1}{\sqrt{1-x^2}}$.
I don't know how to do this second part. Differentiating arcsinx I know how, but arcsiny and arcsin(xy) I don't know what to do. Any pointers?
Thanks

2. 1) d(arcsin(y))/dx= 1/sqrt[1-y^2] (dy/dx)
2) d(arcsin(xy))/dx= 1/sqrt[1-(xy)^2] (d(xy)/dx)

3. Thanks! how could i have forgotten that

4. err, i'm supposed to find dy/dx, what do i do with d(xy)/dx?

5. d(xy)/dx =(y+x dy/dx)