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Activity
BBC

Bbc: Gcse Bitesize: Sine and Cosine Rules

For Students 9th - 10th Standards
BBC provides a three part lesson on solving triangles, by using the sine rule and cosine rule.
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Handout
Cuemath

Cuemath: Cosine Law

For Students 9th - 10th Standards
A comprehensive guide for learning all about the law of cosine with definitions, what is the law, and solved examples.
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Activity
Other

Trig Without Tears: Solving Triangles

For Students 9th - 10th Standards
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.
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Unit Plan
Wolfram Research

Wolfram Math World: Acute Triangle

For Students 9th - 10th Standards
This MathWorld site gives a short discussion on acute triangles with links to related terms and topics. The site offers a discussion on the least number of acute triangles to compose various polygons, and a discussion on the relationship...
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Whiteboard
ClassFlow

Class Flow: The Law of Cosines

For Teachers 9th - 10th Standards
[Free Registration/Login Required] This flipchart defines and uses the law of cosines to find the missing sides and angles of oblique triangles.
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Unit Plan
CK-12 Foundation

Ck 12: Geometry: Laws of Sines and Cosines

For Students 9th - 10th Standards
[Free Registration/Login may be required to access all resource tools.] This concept teaches students to find missing sides and angles in non-right triangles using the Laws of Sines and Cosines.
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Activity
Analyze Math

Analyze Math: Cosine Law Problems

For Students 9th - 10th Standards
Here are four problems to solve using the Law of Cosines. Two are SSS problems; two are SAS problems. Two have detailed solutions; two have answers given only. Notice the link at the bottom that takes you to a Law of Cosines calculator -...
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Primary
Windstream

Ojk's Precalculus Study Page: The Law of Cosines

For Students 9th - 10th Standards
An introduction to solving acute and obtuse triangles by using the law of cosines, including a derivation of the formula. Includes several pistures and examples.
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Unit Plan
Khan Academy

Khan Academy: Laws of Sines and Cosines Review

For Students 9th - 10th Standards
Review the law of sines and the law of cosines, and use them to solve problems with any triangle.
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Activity
Math Is Fun

Math Is Fun: Triangle Identities

For Students 9th - 10th Standards
View examples of triangle identities, equations that are true for all triangles: Law of Sines, Law of Cosines, and Law of Tangents. Follow links to learn more about the purpose and examples of each identity.
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Handout
Georgia State University

Georgia State University: Hyper Physics: Laws of Sines and Cosines

For Students 9th - 10th Standards
At the bottom of this page from the Georgia State University, you will two real-world applications of the Laws of Sines and Cosines (in the context of velocity vectors.)
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Lesson Plan
Oswego City School District

Regents Exam Prep Center: Working on a Rescue Team Lab

For Teachers 9th - 10th Standards
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?...
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Unit Plan
CK-12 Foundation

Ck 12: Trigonometry: Sides of an Oblique Triangle

For Students 10th - 12th Standards
[Free Registration/Login may be required to access all resource tools.] This lesson covers using the Law of Cosines to find the third side of a triangle.
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Unit Plan
CK-12 Foundation

Ck 12: Trigonometry: Sides of an Oblique Triangle

For Students 10th - 12th Standards
[Free Registration/Login may be required to access all resource tools.] Find the side of an oblique triangle using the Law of Cosines.
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Interactive
Government of Alberta

Learn Alberta: Math Interactives: Exploring Trig Ratios

For Students 6th - 8th
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...
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Activity
University of Vienna (Austria)

Trigonometry: Law of Sines

For Students 9th - 10th Standards
This is demonstration of how the law of sines works. It uses Java applets to manipulate the triangle and allows the user to explore what happens to the values of the triangle as the sides are changed.
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Activity
Texas Instruments

Texas Instruments: Numb3 Rs: To Pythagoras and Beyond

For Teachers 9th - 10th Standards
Based off of the hit television show NUMB3RS, this lesson has students discover the Pythagorean relationships of different triangle types. By the end of the lesson, students should be able to take three given side lengths and compute...
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Activity
Other

Karl's Calculus Tutor: Trigonometric Functions

For Students 9th - 10th Standards
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.
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Activity
Analyze Math

Analyze Math: Triangle Problems

For Students 9th - 10th Standards
Here are five triangle problems to solve using the Law of Sines, Law of Cosines, Pythagorean Theorem, and trigonometry. All problems have detailed written solutions included.
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Unit Plan
CK-12 Foundation

Ck 12: Trigonometry: General Solutions of Triangles

For Students 10th - 12th Standards
[Free Registration/Login may be required to access all resource tools.] A summary of when to use the law of cosines or the law of sines to solve triangles.
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Lesson Plan
Alabama Learning Exchange

Alex: Land Surveying Project

For Teachers 9th - 10th
This project resulted from of the collaboration of a computer aided drafting teacher, Chris Bond, and a math teacher, Lee Cable, (Hewitt-Trussville High School) to provide higher math expectations in CT and real life application in...
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Interactive
Calculator Soup

Calculator Soup: Triangle Theorems Calculator

For Students 9th - 10th Standards
Each calculation option has sub-bullets that list the sequence of methods used in this calculator to solve for unknown angle and side values including Sum of Angles in a Triangle, Law of Sines, and Law of Cosines.
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Unknown Type
Khan Academy

Khan Academy: General Triangle Word Problems

For Students 9th - 10th Standards
Solve word problems that involve general triangles using trigonometry. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
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Handout
Analyze Math

Analyze Math: Free Math Tutorials: Triangles

For Students 9th - 10th Standards
The geometry tutorial investigates the definitions and properties of triangles. Topics included are isosceles, equilateral, and right triangles. In addition, the sine and cosine laws of triangles are defined.