Alright. While doing homework i stumbled on these questions. If you can assist me on some, it would be greatly appreciated:

1) Prove that Cos(arcsinx) = (1-x^2)^(1/2)

Find the derivative and simplify:

2) y = (x)(arccosx) - (1-x^2)^(1/2)

3) y = arctan(x-(1+x^2)^(1/2))

4) y = arctan (x/9) + ln9 ( (x-9)/(x+9) ) ^ (1/2) )

and find the limit of

5) Lim as x goes to 0 from the right, arctan(lnx)

Any help would be very much-ly received and appreciated!!