This week in PreCalc we started our trigonometry unit, while practicing what we know from previous years we slowly added in new things such as the sine law, this is something completely new that we haven’t done in previous years. The sine law is the following, a/sin A = b/sin B =c/sin C with the lowercase letters being the measurements of each sides and the uppercase letters that happen to be multiplied by sign being the angle for each letter respectively.

If there is a missing angle and not a missing side which is what the sine law is mainly for, you flip it to sin A/a = sin B/b = Sin C/c and it can work to find the missing angle as well. When using the sine law there is 3 equations to start with but once inputting values you only use 2 equations, leaving 1 variable in the full equation.

The sine law is used for triangles with a missing angle or side that aren’t right triangles and have an angle more than 90 degrees

Here is an example of how to use the sine law to find a missing angle 