Thilak maths

1. http://www.purplemath.com/modules/idents.htm
2. https://www.mathsisfun.com/sine-cosine-tangent.html
3. https://schools.aglasem.com/1200
4. http://www.learncbse.in/ncert-solutions-for-class-10-maths-chapter-8-introduction-to-trigonometry/
5. http://www.excellup.com/classten/mathten/trigonometryexfour1.aspx
6. http://www.schoollamp.com/class-10-tenth/maths/introduction-to-trigonometry-important-formula-trigonometry-class-ten-and-chapter-summary-syllabusmatter-449