User talk:172.78.142.200

August 2020
Hello, I'm DVdm. I noticed that you added or changed content in an article, Trigonometric functions, but you didn't provide a reliable source. It's been removed and archived in the page history for now, but if you'd like to include a citation and re-add it, please do so. You can have a look at the tutorial on citing sources. If you think I made a mistake, you can leave me a message on my talk page. Thank you. - DVdm (talk) 15:24, 21 August 2020 (UTC)