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Lesson Plan
Curated OER

Solving Problems Using Triangle Inequality Theorem

For Teachers 6th
Sixth graders investigate triangles and the inequality theorem. They will collaborate in groups to determine the length of a longest side of a triangle. Then relate the size of the triangle to its angles using protractors, yard sticks,...
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Lesson Plan
Curated OER

Triangle Inequality Theorems Investigation

For Teachers 9th - 10th
Learners estimate and measure triangles. For this geometry lesson, students identify the relationship between three sides and a triangle. They use the inequality theorem to decide if a triangle will be formed or not.
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Worksheet
Curated OER

To Be a Triangle Or Not To Be a Triangle?

For Students 10th
In this triangles worksheet, 10th graders solve and complete 10 different problems that include applying the Triangle Inequality Theorem. First, they use the illustrated triangles and the data table to test the theorem. Then, students...
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Worksheet
Curated OER

Countdown Challenge: Triangle Inequality Theorem

For Students 7th - 8th
In this triangle inequality activity, students test the Triangle Inequality Theorem. They measure the sides of given triangles, identify the type of triangle, and name angles in the triangle. The one-page activity contains 36 problems.
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Performance
Radford University

Triangle Inequality Task

For Teachers 9th - 12th Standards
Not all triangles are created equal. A simple hands-on activity has learners investigate the side lengths of triangles. They use pipe cleaners to determine whether triangles of given side lengths can exist and then use the results to...
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Lesson Plan
Curated OER

Triangle Inequality Theorem

For Teachers 9th - 12th Standards
High schoolers investigate the relationship between angle measures and sides of a triangle and the relationships among the three sides of a triangle. The use of technology (Cabri, Jr.) allows learners to make and test conjectures as they...
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Lesson Plan
Curated OER

Triangle Inequality

For Teachers 4th - 6th
Students discover that the sum of the lengths of any two sides of a triangle must be greater than the third side. They are shown how a triangle is formed using three strips such as that the triangle is seen inside the strips.
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Worksheet
Curated OER

Quiz: Triangle Inequality Theorem

For Students 7th - 8th
In this triangle inequality theorem worksheet, learners determine the lengths of the sides of triangles and identify the measure of angles. This one-page worksheet contains ten triangle theorem problems.
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Lesson Plan
Virginia Department of Education

How Many Triangles?

For Teachers 9th - 11th Standards
Something for young mathematicians to remember: the sum of any two sides must be greater than the third. Class members investigates the Triangle Inequality Theorem to find the relationship between the sides of a triangle. At the same...
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Lesson Plan
Curated OER

Triangle Inequality Theorem

For Teachers 8th - 10th
Students use the inequality theorem to solve triangles and their properties. In this geometry lesson, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length needed to make a...
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Lesson Plan
Curated OER

Indirect Proof and Inequalities in one Triangle

For Teachers 10th
For this geometry worksheet, 10th graders complete an indirect proof and order the sides or angles of a triangle. Also, students determine if a triangle can have sides with the given lengths. The two page worksheet contains twelve...
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Worksheet
Curated OER

Triangle Inequalities Homework

For Students 10th - 11th
In this geometry instructional activity, students solve problems based on the triangle inequality theorem(s) in which determine if the given lengths can form a triangle, given two sides of a triangle determine the range of the third...
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Interactive
CK-12 Foundation

Pythagorean Theorem to Classify Triangles: Missing Angles

For Students 8th - 12th Standards
Learn to use the Pythagorean Theorem with non-right triangles. Pupils use the interactive to discover the relationship between the lengths of sides for acute and obtuse triangles. They compare the squares of the sides of the triangles to...
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Lesson Plan
Curated OER

Triangle Inequality Theorem

For Teachers 7th - 9th
Students identify properties of triangles. In this geometry lesson, students create triangles using three different segments. They make conjectures and predictions.
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Lesson Plan
Curated OER

Toothpick Triangles

For Teachers 4th - 8th
Learners draw a chart (included in the lesson) to use with their investigation. They review terminology of triangles and receive toothpicks to use in the lesson. Beginning with three toothpicks, students form a triangle. They complete...
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Lesson Plan
Curated OER

Drawing Straws

For Teachers 4th
Fourth graders examine the Triangle Inequality Theorem by investigating possible lengths of the sides of a triangle.
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Lesson Plan
Curated OER

Inequalities and Triangles

For Teachers 9th - 10th
Students prove and apply theorems of triangle inequality and hinge theorem. In this geometry activity, students will discuss which triangle is bigger and why. They will use theorems, such as Exterior Angle Inequality or the Pythagorean...
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Worksheet
Mt. San Antonio Collage

Inequalities in a Triangle

For Students 9th - 12th Standards
Stuck with triangle proofs? Take a 180° and provide learners with a guided worksheet that tests their knowledge with triangle inequalities. The questions require different types of proofs that range in levels of difficulty. 
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Assessment
Mathematics Assessment Project

Triangular Frameworks

For Students 7th - 9th Standards
What did the triangle say to the circle? You're pointless! Class members will get the point when they investigate relationships between side lengths of a triangle using the Triangle Inequality Theorem. Pupils then create an algebraic...
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Lesson Plan
Alabama Learning Exchange

Is It a Triangle?

For Teachers 9th - 12th Standards
Learners explore the concept of triangle inequalities.  In this triangle inequality lesson, students cut spaghetti noodles into given lengths.  Learners use the noodles to complete a worksheet about triangle inequalities.  Students...
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Worksheet
Curated OER

Triangles

For Students 10th
In this triangles worksheet, 10th graders solve and complete 22 different problems related to various types of triangles. First, they name the shortest and longest sides and the smallest and largest angles in each of triangles...
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Lesson Plan
Curated OER

Triangles Congruency Theorems

For Teachers 10th
Tenth graders investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two angles are formed by...
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Lesson Plan
Curated OER

Triangle Sum Theorem

For Teachers 10th
Tenth graders investigate the theorems of angles and lines to prove triagle sum theorem. In this geometry lesson plan, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review...
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Lesson Plan
Curated OER

Napolean Triangle

For Teachers 9th - 11th
Students investigate the Napoleon triangle theory. In this polygon lesson, students  differentiate between the boundary points, interior and lattice point of a polygon. They apply concepts of equilateral triangles to solve problems.