Can someone tell me the solution of following problems:

1.

$\displaystyle (sin(pi/2 - x) - cos^3x)/(sin(2x + 4pi))$

My solution sinx/2

2.

I have to get other 2 values

sinx=2/3

_______

sin2x = ?

tan(pi/4-x) = ?

3.

y = x/5 - 1

y = -5x/4 + 1

k1 = 1/5

k2 = -5/4

$\displaystyle tan()=|(k2-k1)/(1+k1*k2)|$