This page from MathWorld.com gives a good explanation of the Law of Cosines, which relates the lengths of the legs of a triangle to the angles. This site shows how the formula is derived, along with a triangle to clarify variables. Also...

Great application of trig and introduction to the trig functions. Also found here are the Law of Sines and Law of Cosines as well as other trig topics to review.

Investigate the cosine, sine, and tangent ratios of trigonometry using this interactive Learn Alberta math resource. Students will use these ratios to determine a right triangle's unknown side or angle. Be sure to follow the link to the...

These two navigation problems employ the use of the law of sines or cosines and basic trigonometry. Each problems includes links to a sketch of the problem for visual help, and to a solution.

Based off of the hit television show NUMB3RS, this lesson has students set up a search region for a yacht that sank into the ocean. Using cylindrical coordinates and a little trigonometry, students are able to block off a certain portion...

Just about everything you need to know about trigonometry can be found here. Interactive examples and demonstrations help to enhance the lessons. Although not required, the tutorial uses Live Math and Scientific Notebook.