### 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) ~~**1**) How can I simplify the ~~function?
2) ~~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)