Trigonometry - Sine and Cosine Rule

A short video on historical use of Trigonometry in ancient Indian astronomical observatories...



When we aren't dealing with right angle triangles then the Sine Rule and Cosine Rule become very important:

For the Sine Rule we are dealing with a situation involving two sides and two angles (one of which will be unknown), for the Cosine Rule you need 3 sides and one angle (again one of which is unknown).