The Precalculus Trigonometry TI-83/TI-84 Tutorial uses four special characters frequently, the Greek letters delta, pi and theta, and the degree symbol. These characters have been specified in the HTML code using universal character set (unicode) references, which is a way of designating a character that is independent of a font type. In most cases, getting your browser to properly display these characters is simply a matter of choosing an appropriate font in your browser. The following table offers a few common fonts that should be able to interpret the four characters used in this tutorial correctly (different fonts will handle different ranges of unicode values).

Try choosing some different fonts in your browser until the set of characters shown below are all displayed properly (the decimal versions are given for reference). We have given a link to an internet web resource that provides instructions for setting the font in various browsers.

Enabling Unicode in Certain Browsers
Unicode Capable Browsers

For more information on unicode fonts, you might try the following internet resources which go into greater detail. If all else fails, then you may need to update your browser to a more current version or switch to a different browser.

Alan Wood's Unicode Resources
Windows Fonts that Support Unicode
Macintosh Fonts that Support Unicode