Trig Unit 5: Law of Sines and Cosines Interactive Notebook

Unit 5: Law of Sines and Cosines

Pg 49-50 Started this unit with the investigations by Illumination that develop the Law of Sines and Cosines. Then we used these pages to practice the formulas.

 Pg 51-52 These pages cover three cases of the ambiguous case with the SSA postulate. After doing the problems, students cut and paste the correct pictures.

Pg 53-54 Similar to our Law of Sines pages, we developed the formulas and then practiced the Law of Cosines.

Pg 55-56 We practiced word problems by first using the COS diagram (Thanks Meg Craig!) to decide when to use LoC and when to use LoS.

Here are the files:

See my update to this unit this year with area of oblique triangles.


  1. I'm trying to make sense of these two laws and am a bit confused on your example page for law of sines. It has a triangle with 2 sides and 1 angle. I thought you couldn't use law of sines for that. I'm sure there's a reason you can, I just don't quite understand it! Help!

    1. Good point- I didn't notice that. The SSA is the ambiguous case because there are two possible triangles so two possible answers. My example shows just one answer.