Curated OER
Law of Cosines
In this Law of Cosines worksheet, 10th graders solve 10 different problems related to applying the Laws of Cosine. First, they determine the length of a side rounded to the nearest integer. Then, students determine the largest angle of a...
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.
Khan Academy
Khan Academy: Solve Triangles Using the Law of Cosines
Solve missing triangle measures using the law of cosines. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
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.