derivative

find the derivative of the following:

1. f(x)=x^2(arcsin x) (find the first derivative)

2. f(x)=sin x/1-cos x (find the second derivatives)

3. d/dt [(t)(d/dt)(cos t^2)]

4. given that y=u^2 , u=sec x , x=(1+t)^2. Express dy/dt in terms of t.

5. To estimate the height of a bridge, a stone(initially at rest) is dropped from the bridge to the water below. If the splash is heard after 4s, find the height of the bridge. Assume that the speed of the sound is 344ms-1.

(a)41m (b)51m (c)61m (d)71m (e)81m