please check this article to create chart in sharePoint hosted app

http://tomvangaever.be/blogv2/2014/03/how-to-create-charts-from-sharepoint-2013-list/

And also i want to know more about how to use webpartpage chartviewwebpart?

Below link helps to use the webparts in apps

http://www.sharepointnutsandbolts.com/2013/08/working-with-web-parts-within.html

Check this article to create charts in SharePoint hosted app

http://tomvangaever.be/blogv2/2014/03/how-to-create-charts-from-sharepoint-2013-list/

And also i want to know more about how to use webpartpage chartviewwebpart?

Below link helps to use the webparts in apps

http://www.sharepointnutsandbolts.com/2013/08/working-with-web-parts-within.html