# Sage fails to evaluate this expression.

Sage doesn't seem to compute correctly `8*sin(pi/9)^3 - 6*sin(pi/9) + 3^(1/2)`

which is plain zero.

Sage fails to evaluate this expression.

asked
**
2015-03-29 04:12:06 -0500
**

This post is a wiki. Anyone with karma >750 is welcome to improve it.

Sage doesn't seem to compute correctly `8*sin(pi/9)^3 - 6*sin(pi/9) + 3^(1/2)`

which is plain zero.

add a comment

2

Sage can compute it, but you must help it with reduce_trig():

```
a = 8*sin(pi/9)^3 - 6*sin(pi/9) + 3^(1/2)
a.reduce_trig()
0
```

Asked: **
2015-03-29 04:12:06 -0500
**

Seen: **93 times**

Last updated: **Mar 30 '15**

Displaying mathematical notation as "strings"

Evaluating a list of multivariate equations at random values.

evaluate (simplify) trigonometric expression

Idea behind not evaluating symbolic equations

problems with symbolic integration and then numerical evaluating

Trigonometric Equation Solving: Not Terminating

Copyright Sage, 2010. Some rights reserved under creative commons license. Content on this site is licensed under a Creative Commons Attribution Share Alike 3.0 license.