How to Execute html code in text area

i am giving text area like this showing below, in that i am rendering
one page

now that page is showing in text area but html code is not executing in
text area,its showing as it is html tags in that text area

<%=text_area 'per','body',:cols=>80,:rows=>20,:value=>"#{render
:partial=>'printletter'}"%>

Use tinymce.