# Trigonometric equality (with arctan and arcsin)

Hi,

I found a strange issue:

```
ex = (arctan(1/2) + arcsin(sqrt(5)/5) == arctan(4/3))
bool(ex)
```

And it gives False.

A simple numeric approximation allows to see that it's true, and wolfram alpha for instance gives the correct answer. But why is it like that and how can I fix it?

Thanks

In sagecell,

`giac('simplify(tExpand((arctan(1/2) + arcsin(sqrt(5)/5) - arctan(4/3))))')`

returns $0$.`tExpand`

is a shortcut forexpand trascendental expressions.Seems to work. Thanks for the terminology.