# Solve equations with sin(x)

Hi. I want to know why sage can't solve the euqations: [4*sin(x)+y==5,sin(x)==y] (It's so easy!)and it just gives back: [sin(x)==y,y+4*sin(x)==5]. Can you help me?

Solve equations with sin(x)

*sin(x)+y==5,sin(x)==y] (It's so easy!)and it just gives back: [sin(x)==y,y+4*sin(x)==5]. Can you help me?

2

Congratulations, you have found a bug! I have reported it at

0

Solving equations is done through the solve command, which is documented here. I went to a Sage cell server and typed in:

```
solve(5-4*sin(x)==sin(x),x)
```

and got an answer: [x == 1/2*pi]. Of course, since the trig functions are periodic there are an infinite number of solutions.

Since you haven't given the code that resulted in the output you describe, it's impossible for me to know what went wrong. Always provide your code; it makes it easier to diagnose what is wrong.

On sagenb.org using var('x,y'); solve([y==sin(x),y+4*sin(x)==5],x,y) I get [y == sin(x), y + 4*sin(x) == 5] as a solution

Asked: **
2014-07-31 20:50:32 -0500
**

Seen: **142 times**

Last updated: **Aug 04 '14**

Please Append 'solve' Help Documentation

Evaluating symbolic expressions

(Unexpanded) symbolic inequalities yield erroneous results

Extended Euclid with polynomials

Using sage to derive symbolic finite difference approximations to differential equations.

Solve for all values of a variable

Solving trigonometric functions

Solve system of equations with additional conditions in sage

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What command did you give?