Sine Rule

In this video we are going to discover what the sine rule is and how it works. For right angle triangles, we can use Pythagoras and SOHCAHTOA to find missing sides and missing angles. However, not every triangle is a right-angle triangle. For non-right angle triangles we have the sine rule and the cosine rule. The sine rule can be used to find either missing sides or missing angles in any triangle (right angle or not). The sine rule is based on opposite pairs - an angle and the opposite side. We therefore label sides as a, b and c, and angles as A, B and C. We can then simply substitute in the values to find the missing side or the missing angle. If we're looking for a missing side, we use the formula (a / sinA) = (b / sinB). Whereas to find a missing angle we use (sinA / a) = (sinB / b).