50g

After entering an equation with the equation writer, with one variable
such a 'x', how do you evaluate 'x' for the equation?
It seems like using the equation writer might be easier than 
programming.  For programming, do you start with << >> button, and 
finish with the left arrow prg button?
My old HP15c was simple to program;  an example would be:
g prg
f prgm
f LBL A
STO 0
SIN
1/x
STO1
RCL 0
g x^2
3
/
RCL 1
X
g RTN
g PRG

if x = 3, then f(x) = 21.26  (using radians)
Could this be programmed easier with the HP50G?
Thanks