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Lesson Plan
Curated OER

Law of Cosines Practice

For Teachers 8th - 10th
Students practice solving problems with non-right triangles. In this precalculus lesson plan, students define and identify the properties of the Law of Cosine. They solve problems and investigate the history behind Cosine.
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Lesson Plan
Curated OER

Some More Trigonometry

For Teachers 9th - 10th
Students define the law of cosine and its correct usage. For this trigonometry lesson, students define the law of Heron's area formula and use it to solve problems. They review other trigonometric values and identify the identities.
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Lesson Plan
Curated OER

Law of Cosines Word Problem

For Teachers 10th - 11th
Students 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.
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Lesson Plan
Curated OER

The Laws of Sines and Cosines Made Simple!

For Teachers 10th - 12th
Young scholars 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. Young scholars use their triangle tool to aid in solving problems...
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Lesson Plan
Curated OER

Algebra And Trigonometry - Week 3: Law of Sines

For Teachers 12th - Higher Ed
In this law of sines worksheet, pupils read story problems. They use both algebra and the law of sines and cosines to solve problems. This two page worksheet contains seven problems.
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Lesson Plan
Curated OER

Trigonometry Involving Figures - Week 11

For Teachers 10th - 11th
In this trigonometry worksheet, pupils use trigonometric functions to determine the measurement of angles and the length of sides in given figures. Most figures are comprised of rectangles containing parallel and perpendicular lines, as...
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Lesson Plan
Curated OER

Journey of the Nez Perce

For Teachers 10th - 12th
Students 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...
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Lesson Plan
Curated OER

River Width

For Teachers 6th - 8th
Students determine the level of accuracy needed for computations involving measurements and irrational numbers. They use the correct number of digits in computation to achieve an appropriate unit or level of accuracy when solving...
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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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Handout
Wolfram Research

Wolfram Math World: Heron's Formula

For Students 9th - 10th
This site provides a detailed overview of Heron's Formula. Content includes a definition, example, and formula.
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Activity
Other

Trigonometry: A Crash Review

For Students 9th - 10th
This site really is a crash review on trigonometry! Formulas, functions - you name it, it's covered! Also includes self quizzes for practice.
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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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Unit Plan
Oswego City School District

Regents Exam Prep Center: Law of Sines and Law of Cosines

For Students 9th - 10th Standards
This tutorial examines the law of sines and the law of cosines. Includes class notes, examples, and a variety of practice problems with solutions. The teacher resource consists of a lab that utilizes the law of sines and the law of cosines.
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Handout
Wolfram Research

Wolfram Math World: Law of Cosines

For Students 9th - 10th Standards
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...
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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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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
Texas Instruments

Texas Instruments: Numb3 Rs: Where's Cheetah?

For Teachers 9th - 10th
Based off of the hit television show NUMB3RS, this lesson has students set up a search region for a yacht that sank into the ocean. Using cylindrical coordinates and a little trigonometry, students are able to block off a certain portion...
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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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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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Handout
Other

Dans Math: Lessons: Trigonometry

For Students 9th - 10th
College professor Dan Bach reviews basic trig concepts, including trig functions, right triangles, circles, radians, and polar coordinates. Site includes animated graphs and detailed examples.
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eBook
Math Planet

Math Planet: Algebra 2: Cosines

For Students 9th - 10th Standards
Defines and explores the law of cosines through examples and a video lesson. [1:41]
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Unknown Type
McGraw Hill

Glencoe Mathematics: Online Study Tools: Self Check Quiz on Law of Cosines

For Students 9th - 10th Standards
The online assessment demonstrates knowledge of Algebra II. The questions test students on the law of cosines.
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Unit Plan
CK-12 Foundation

Ck 12: Determination of Unknown Angles Using Law of Cosines

For Students 10th - 12th Standards
[Free Registration/Login may be required to access all resource tools.] Find an unknown angle of a side side side triangle using the Law of Cosines.
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Activity
Varsity Tutors

Varsity Tutors: Hotmath: Graphing Calculator Practice: Right Triangles and Trigonometry

For Students 9th - 10th Standards
Practice using your graphing calculator for solving right triangle trigonometry and non-right triangle trigonometry. If you get stumped or if you would like to check your work, then select the View Solution button, which is located...