Obradovic, Dragan, Lakshmi Narayan Mishra, and Vishnu Narayan Mishra. “Basic Trigonometric Identity”. European Journal of Science, Innovation and Technology 1, no. 3 (September 5, 2021): 22-27. Accessed April 18, 2024. https://ejsit-journal.com/index.php/ejsit/article/view/18.