tinymce setContent and setMode Operation

Question

I'm Having a Problem with tinymce,

Editor textarea is located under a div object,

tinymce.get("#DV_Gorev_Genel_Liste #TXA_GorevTanimlamaPencereAlani_Genel_Aciklama").setContent('');
tinymce.get("#DV_Gorev_Genel_Liste #TXA_GorevTanimlamaPencereAlani_Genel_Aciklama").setMode('design');

I Want to Use It Under Selector As Above, But I Think It's Not Supported

When I research, I see that it should only have a textarea id.

How can I use setContent and setMode?

I am waiting for your help, good work...