https://www.khanacademy.org/math/ncert-class-10/xd6a17b08edbd2443:introduction-to-trigonometry-ncert-new Check out the whole chapter on Khan Academy!
Curated by: Khan Academy India - English (9 videos)
https://www.khanacademy.org/math/ncert-class-10 Let's try to prove a trigonometric identity involving sin, cos, and tan in real-time and learn how to think about proofs in trigonometry. Courses on Khan Academy are always 100% free. Start practicing—and saving your progress—now! Khan Academy India is a nonprofit organization with the mission of providing a free, world-class education for anyone, anywhere. We have videos and exercises that have been translated into multiple Indian languages, and 15 million people around the globe learn on Khan Academy every month. Support Us: https://india.khanacademy.org/donate Created by Aanand Srinivas.