Law of Cosines Teacher Resources

Sal derives the Law of Cosines using a method similar to the wayward ship captain word problem he solves in another video. This video provides a good review of using the SOH-CAH-TOA model, the Pythagorean Theorem, some of the basic trig...

Build upon the Pythagorean Theorem with the Law of Cosines. The 10th part of a 16-part series introduces the Law of Cosines. Class members use the the geometric representation of the Pythagorean Theorem to develop a proof of the Law of...

Take me out to the trig class. Individuals use an interactive to see how angles on a baseball field change as the position of two runners change. A set of challenge questions has them apply the Law of Cosines to solve problems.

In this college level trigonometry worksheet, students apply the Law of Sines and the Law of Cosines to solve triangles. The four page worksheet contains forty-four problems. Solutions are not provided. 

Use the Law of Cosines and the Law of Sines to solve problems using the sums of vectors. Pupils work on several different types of real-world problems that can be modeled using triangles with three known measurements. In the process,...

Catch a great resource! Individuals use an interactive that allows them to move players on a baseball field. They calculate distances between players using the Law of Cosines.

Baseball is all about math. Young baseball and mathematics enthusiasts determine the distance between players on a baseball field using the Law of Cosines. An interactive helps them find relevant distances and angles to use in their...

Zip this resource into your lesson plans. Here is an interactive that shows how angles and lengths change based on conditions for a zip line. Scholars use the Law of Cosines to solve problems in this context.

In this proofs worksheet, students construct 1 proof of the law of cosines.  Students construct a right triangle within a circle to  prove the law of cosines.

Drawing triangles is easy, even if you have to calculate the exact length of its sides. Scholars use the Law of Cosines to find missing sides of triangles. An interactive helps them check their answers.

Students practice solving problems with non-right triangles. In this precalculus lesson, students define and identify the properties of the Law of Cosine. They solve problems and investigate the history behind Cosine.

Learners solve problems using the law of cosines. In this precalculus lesson, students meet different criteria as they solve problems. They apply the formula for cosines to solve word problems.

Explore triangle problems that require the Law of Sine or Law of Cosine. A straightforward lesson focuses on deciding when to use each law. The instructor presents several triangles for pupils to consider and describes patterns in the...

Students investigate trigonometry.  In this Algebra II/Pre-calculus/Trigonometry lesson, students explore Islamic achievements in mathematics as they calculate angles and distances using the Law of Sines and the Law of Cosines. ...

In this trigonometry worksheet, students solve 15 triangle problems.  Students use the law of sines and law of cosines to find the missing angles and side lengths of a triangles.

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...

In this Pre-calculus/Trigonometry activity, students use the laws of sines and cosines to solve triangles. The four page activity contains thirteen problems. Answers are not included.

Not all triangles are right! Pupils learn to tackle non-right triangles using the Law of Sines and Law of Cosines. After using the two laws, they then apply them to word problems. 

Increase the level of assessment rigor with the test of performance tasks. Topics include similar triangles, trigonometric ratios, Law of Sines, Law of Cosines, and trigonometric problem solving. 

Get straight answers on a curved grid. An interactive has learners apply the Law of Cosines to find the distance between two points on the polar coordinate plane. The pupils use the radii lengths and the angle between the two radii to...

Solving triangles is a breeze. Young boat enthusiasts solve problems involving triangles in the context of sails on a boat. They must apply different strategies, including the Law of Cosines and area formulas.

Students explore the concept of law of sines and cosines. In this law of sines and cosines lesson, students construct a triangle tool from card stock and markers. Students use their triangle tool to aid in solving problems involving...

Students define the law of cosine and its correct usage. In this trigonometry instructional activity, students define the law of Heron's area formula and use it to solve problems. They review other trigonometric values and identify the...

Pupils study the retreat of the Nez Perce Native Americans into Montana while tracing their journey on a map. They use the law of cosines to solve problems based on the navigational methods of the Nez Perce. They work with both the law...