Even though you don't mention about page3.html in sitemap, bot's will crawl and index this page.
When ever a bot come to crawl our site first it will look for Sitemap, because it is a guide line from google to create and submit sitemap to the search engines. So it is nothing but we are providing the total website information in one file. In other terms it is called Search engine friendly.
And also if bot's encountered any problem while crawling this page3.html then they won't index this page.
Thank you..
