Wolfram Research
Wolfram Math World: Law of Cosines
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...
Math Is Fun
Math Is Fun: Solving Triangles
Find guidelines to help you "solve" triangles, which means finding the value of missing sides and angles. Provided are examples of six scenarios in which you can solve a triangle's missing measurements, as well as relevant equations,...
Georgia State University
Georgia State University: Hyper Physics: Law of Cosines
This page from the Georgia State University provides a definition of the Law of Cosines. Also includes a "calculator" to help you find side lengths and opposite angles when you are given either three sides or two sides and a third angle.
Cut the Knot
Cut the Knot!: The Law of Cosines (Cosine Rule)
This site from Cut The Knot provides an overview of the law of cosines, complete with an explanation of the law and a proof of the law.
Cut the Knot
Cut the Knot!: Analogues and Generalization of the Pythagorean Theorem
This site discusses the theorems and other findings which are directly related to the fundamental Pythagorean theorem. Be sure to click on the link to information on Pythagorean theorem to find several proofs of the theorem.
Oswego City School District
Regents Exam Prep Center: Working on a Rescue Team Lab
Your students are part of the Yellowstone National Park rescue team which has just been dispatched to help located a downed plane. How can they effectively use the Law of Sines and the Law of Cosines to assist them in finding the plane?...