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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. For this geometry lesson, 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
Curated OER

Proving Quadrilaterals

For Students 10th
For this geometry worksheet, 10th graders identify the missing angles using the polygons sum conjecture. They measure exterior and interior angles using their angle theorems. There are 63 problems.
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Lesson Plan
Curated OER

Exterior and Interior Angles of Triangles

For Teachers 10th
Tenth graders explore the exterior and interior angles of triangles. They use a theorem in order to prove a theorem about all polygons. Students use the theorem and its applications to find the angles of different types of triangles.
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Lesson Plan
EngageNY

Similar Triangles in Circle-Secant (or Circle-Secant-Tangent) Diagrams

For Teachers 9th - 12th Standards
First angle measures, now segment lengths. High schoolers first measure segments formed by secants that intersect interior to a circle, secants that intersect exterior to a circle, and a secant and a tangent that intersect exterior to a...
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Worksheet
Curated OER

Quiz: Triangle Inequality Theorem

For Students 7th - 8th
In this triangle inequality theorem worksheet, students 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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Assessment
Charleston School District

Pre-Test Unit 2: Similar and Congruent

For Students 8th Standards
A pre-test contains questions about transformations that lead to congruent and similar images. It also covers angle relationships associated with triangles and parallel lines intersected by a transversal. 
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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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Worksheet
Mt. San Antonio Collage

Isosceles Triangles and Special Line Segments

For Students 9th - 12th Standards
Under which conditions can a triangle be classified as isosceles? High schoolers practice identifying isosceles triangles and special line segments, including angle bisectors, medians of triangles, and perpendicular bisectors of sides of...
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Interactive
Curated OER

Polygons Multiple Choice

For Students 9th - 10th
In this geometry worksheet, students identify the interior and exterior angles using the angle sum theorem. They identify and solve quadrilaterals using properties of quadrilaterals. There are 12 questions with an answer key.
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Printables
Virginia Department of Education

High School Mathematics Geometry Vocabulary Word Wall Cards

For Teachers 9th - 10th
Having a good working knowledge of math vocabulary is especially important for geometry learners. Here are 119 pages worth of wonderfully constructed definitions, constructions, formulas, properties, theorems, and postulates. This is a...
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Worksheet
Curated OER

Proving Lines Parallel

For Students 10th
In this proving lines parallel worksheet, 10th graders solve 10 different types of problems that prove that various lines are parallel to each other. First, they find the value of x so that line a is parallel to line b. Then, students...
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Assessment
Charleston School District

Review Unit 2: Congruence and Similarity

For Students 8th Standards
Review for the test with a comprehensive list of terms and concepts for the unit on congruence and similarity. It divides divides the sections in the order of the lessons presented during the unit. 
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Lesson Plan
Curated OER

Triangle Conjectures

For Teachers 10th
Tenth graders investigate the theorems of ASA, AAS, AAA and ASA. For 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

Math: Tangents

For Teachers 9th - 10th
Students discover how to recognize tangents and how to use their properties. They investigate and use the properties of angles, arcs, chords, tangents, and secants. Students use two tangents and the properties of similar triangles to...
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Worksheet
Curated OER

Properties of Geometry

For Students 10th
In this properties of geometry worksheet, 10th graders solve and complete 12 different problems that include various theorems. First, they draw a figure that illustrates the SAS inequality property. Then, students prove that two line...
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Lesson Plan
Curated OER

Strongest Polygon

For Teachers 9th - 12th
Students define and identify shapes by name. In this geometry lesson plan, students construct, identify and compare polygons based on the number of sides. They classify each shape based on their angle sum theorem.
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Lesson Plan
Curated OER

Inscribed Quadrilaterals and Parallelograms

For Teachers 9th - 10th Standards
Learners differentiate between inscribed quadrilaterals and parallelograms. In this geometry lesson, students identify the shaped of the polygons when it is inscribed inside of a circle. They calculate the missing angles of the inscribed...
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Lesson Plan
Curated OER

The Truth About Triangles And Proofs

For Teachers 9th - 12th
Learners engage in a lesson that is about the classification of triangles and the mathematical proofs involved in working with them. They work on a variety of problems that are created by the teacher with the focus upon the importance of...