# Simplify, Solve Equation and use solution

Hi, I'm new to sage, and have the following question: I have the following code:

`x,y=var('x y') f(x,y)= sin(x)*cos(y)+sin(y)*cos(x) f.full_simplify show(f(x,y)) s1=solve([f(x,y)==1],x,y) show(s1)`

Sage obiously doesn't simplify the function f... (simple trigonometric expression). And it doesn't solve it.

**1**) How can I simplify the function?

**2)** How can I use the result? For example: I have as an result:
solution=[x == -1]
How can I replace this x in an other function (example: sin(x)).
In mathematica I would do: sin(x) /. solution
or manually: sin(x) /. x->(-1)