Government of Alberta
Learn Alberta: Math Interactives: Exploring and Solving Triangles
This multimedia Learn Alberta math resource focuses on the many triangles that are found in our everyday environment. The accompanying interactive component asks students to find triangles in a picture and to solve for the missing angles...
Maths Challenge
Maths challenge.net: Perpendicular Construction
This is a "three star" geometry problem where prior math problem skills and proof experience is recommended to solve this "Perpendicular Construction" problem.
Maths Challenge
Maths challenge.net: Measuring Mountains
Use your triangle solving skills to solve this triangle problem and then apply it to the real world.
National Council of Teachers of Mathematics
Nctm: Illuminations: Tube Viewer Simulation
A computer simulation of viewing through various lengths of tubes at different distances. The simulation also has an exploration of focus questions. [Requires Java.]
BBC
Bbc: Gcse Bitesize: Sine and Cosine Rules
BBC provides a three part lesson on solving triangles, by using the sine rule and cosine rule.
Maths Challenge
Maths challenge.net: Corner Circle
This is a "three star" geometry problem where prior knowledge of circles and triangles is recommended to solve this circle in the corner problem.
Other
Trig Without Tears: Solving Triangles
This page provides a good explanation of how to solve oblique triangles (triangles containing no right angles.) The Law of Cosines section is about halfway of the way down the page.
Other
Brown Math: Remembering Trig Identities
Faced with a large number of trigonometric identities, students tend to try to memorize them all. This site the emphasis is on understanding how the functions work and on memorizing only about a half dozen of them - all the others work...
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,...
Math Is Fun
Math Is Fun: Trigonometry
Students explore trigonometry concepts through this collection of definitions, lessons, examples problem-solving steps and strategies, and practice problems. Topics include solving triangles, trigonometric functions, theorems, and the...
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.