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 see how we can write all the other trigonometric ratios in terms of Sine using trigonometric identities. 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.