we got a bunch of review problems for the test thats coming up in a few days, I got most of them figured out but am stuck on these 3 if anyone could give me a few pointers of where to head

1. **Solved** Code:

TANx + TAN^3x + SINx
---------------------- = COSx + SEC^2x
TANx
TANx(1 + TAN^2x) + SINx
-------------------------- =
TANx
TANx(SEC^2x) + SINx
--------------------- =
TANx
(SEC^2x) + SINx =

2. **Solved** Code:

COS(x+y)
--------- = 1 - TANxTANy
COSxCOSy
COSxCOSy - SINxSINy
--------------------- =
COSxCOSy
COSxCOSy - TANxTANy =
not sure how to turn COSxCOSy into 1

3. Code:

SIN3x COS3x
------ - ------ = 2
SINx COSx
SIN(x+2x) COS(x+2x)
--------- - ---------- =
SINx COSx
SINxCOS2x + COSxSIN2x COSxCOS2x - SINxSIN2x
----------------------- - ----------------------- =
SINx COSx
COSxSINxCOS2x + COS^2xSIN^2x - SINxCOSxCOS2x - SIN^2xSIN^2x
--------------------------------------------------------------- =
SINxCOSx
COS^2xSIN2x -SIN^2xSIN2x
---------------------------- =
SINxCOSx
COS^2x(2SINxCOSx) - SIN^2x(2SINxCOSx)
------------------------------------ =
SINxCOSx
2SINxCOSx(COS^2x - SIN^2x)
----------------------------- =
SINxCOSx
2(COS^2x - SIN^2x) =

if anyone could give me suggestions of where to go for the next steps in these, that would help me out alot, I'll post back if I figure anything out in the mean time