An "angle button"... indicates a reference to an angle, perhaps?  Our software is focused on algebraic manipulations and some trigonometry functions may be used (sin, cos, tan) but no means of entering an angle is available. 

If you wish to share a specific problem example then please do so. Email is a bit tough on algebraic expressions, so the best way to communicate via email is through a scanned image, screenshot or even a digital photo all work well, as they allow us to see the problem in its original context.