I am stuck on these last three:

Question #1

My Answer:

-tan^2(x)+1= sec^2(x).

-sec/csc= tan (x)

Question#2

Solve the following for x

:My Answer

-Divide both sides by 3

- take the sq. root

-cot(x)=sqrt3

-tan of sqrt3 = pi/3

So is pi/3 my answer?

Question#3.

Rearrange the following equation to give an expression for dydx in terms of x and y.

My Answer:

Lost! Where do I begin?!

TIA as always!