As the site is being served by Linux servers, the path is case sensitive.
In order to make this work, replace emoticons with Emoticons in the provided url.
Also, in a URL, replace the backslash (\) by a forward slash (/).
The following HTML code should properly display the image
<img src="https://stackoverflow.com/questions/17141612/images/Emoticons/cool.png" alt="hi" class="inline"/>